Wireless communication circuit and wireless communication apparatus using the same

ABSTRACT

A wireless communication circuit in accordance with the present invention, is the wireless communication circuit having an amplifier for amplifying a signal, includes an amplification route in which the signal passes through the amplifier; a bypass route for bypassing the amplifier; and a route-selector for selecting one of the amplification route and the bypass route. This arrangement prevents an amplification of a signal, being transmitted or being received, when a communication counterpart is in a close distance, thereby reducing an unnecessary power consumption.

This nonprovisional application claims the benefit of U.S. ProvisionalApplication Ser. No. 60/587,029 filed on Jul. 13, 2004, and claimspriority under 35 U.S.C. § 119(a) on Patent Application No. 2003-341573filed in Japan on Sep. 30, 2003, and Patent Application No. 2004-2069494filed in Japan on Jul. 13, 2004, the entire contents of all of which arehereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a wireless communication circuit (a circuitfor use in wireless communication) suitable for use in a card typewireless communication apparatus having a wireless communicationfunction in which Direct Sequence Spread Spectrum (DSSS) is used, suchwireless communication apparatus used by being connected to (a) aninformation terminal device such as a personal computer, an ADSL(Asymmetric Digital Scriber Line) modem, a wireless access-point, and awireless router and the like; or (b) a household audio visual equipmentsuch as a TV (television), DVD (Digital Versatile Disc) player, and thelike. This invention also relates to a wireless communication apparatusincluding the same, and a wireless communication system using the same.

BACKGROUND OF THE INVENTION

First, a spread spectrum in a wireless is described below. Usually, acommunication using the spread spectrum technology is as follows: amodulated input baseband signal for sound or like is modulated at atransmitting end thereby preparing a modulation signal; the modulationsignal is subjected to spectrum spreading by using a spreading code atthe transmitting end, thereby preparing a spread spectrum signal; andthen the spread spectrum signal is transmitted as a high frequencysignal to a receiving end reception-performing communicationcounterpart), which is a communication counterpart of the transmittingend (transmission-performing communication counterpart). The spreadspectrum signal sent from the transmitting end, which is a communicationcounterpart of the receiving end, and received by the receiving end, isthen demodulated (despread) at the receiving end, by using the samespreading code used in the transmittance end.

Direct Sequence Spread Spectrum (Hereinafter referred to as “DSSS”) andFrequency Hopping Spread Spectrum (Hereinafter referred to as “FHSS”)are known as communication methods using the spread spectrum. DSSSspreads a signal over a continuous frequency band, by widely spreadingthe signal of a narrowband modulation wave by multiplying the signal byusing a spreading code. FHSS, such as Bluetooth (registered trademark),spreads a signal within a frequency band by randomly switching overfrequencies of a carrier wave within the frequency band in accordancewith the diffusion code, the carrier wave being used in communicationwith the communication counterpart.

The following describes a conventional card type wireless communicationapparatus. FIG. 21 is a block circuit diagram showing schematicconfiguration of the conventional card type wireless communicationapparatus. The conventional card type wireless communication apparatus50 shown in FIG. 21 is so configured that an antenna 51 is connected toa receiver circuit 52, and to a transmitter circuit 57.

The receiver circuit 52 includes an amplifier 53, a mixer circuit 54,and a demodulator circuit 55. The antenna 51 is connected to a basebandsignal processing circuit 61 through the amplifier 53, the mixer circuit54 and the demodulator circuit 55.

The transmitter circuit 57 includes a modulator 60, a mixer circuit 59,and an amplifier 58. The baseband signal processing circuit 61 isconnected to the antenna 51 through the modulator 60, the mixer circuit59, and the amplifier 58. The mixer circuit 54 and the mixer circuit 59are connected to a local oscillator 56.

Further, the baseband signal processing circuit 61 is connected to aconnector 65 through an interface circuit 62, and the receiver circuit52, the transmitter circuit 57, and the baseband signal processingcircuit 61 are connected to a circuit control section 63. A power supply64 is connected to the connector 65 and each of the above-describedcircuits in the card type wireless communication apparatus 50.

Next described is operation of the conventional card type wirelesscommunication apparatus 50 shown in FIG. 21. A spread spectrum signal(e.g. 2.4 GHz-band) from the communication counterpart (that is, thetransmitting end) is received by the antenna 51 of the receiving end.Then, in the receiving end, the spread spectrum signal is amplified bythe amplifier 53, and is applied to the mixer circuit 54. The spreadspectrum signal, which is the thus received high frequency signal, isdemodulated to a baseband signal by the mixer circuit 54 and thedemodulator circuit 55. The baseband signal then undergoes a necessarysignal processing conducted by the baseband signal processing circuit61, and is output through the interface circuit 62 and the connector 65to an information terminal device (not shown), such as a personalcomputer (PC) or the like.

At the transmitting end, a data signal being inputted from theinformation terminal device (not shown) through the connector 65 and theinterface circuit 62 undergoes the necessary signal processing conductedby the baseband signal processing circuit 61, and is spread to a spreadspectrum signal (e.g. 2.4 GHz-band) by the modulator 60 and the mixercircuit 59. The data signal is then amplified by the amplifier 58, andis transmitted via the antenna 51 to the communication counterpart (thatis, the transmitting end).

The circuit-control section 63 controls the operation of the receivercircuit 52, the transmitter circuit 57, and the baseband signalprocessing circuit 61. The power supply 64 receives power through theconnector 65 from the information terminal device (not shown) such as aPC or the like, and supplies power+B to each circuit described above inthe card type wireless communication apparatus 50.

The local oscillator 56 generates necessary frequency signals (e.g. 2.4GHz) for the operation of each of the mixer circuits 54 and 59.

For controlling an RF signal of a wireless section, different types ofcommunication apparatuses modulate and demodulate signals of differentfrequencies and levels after converting the frequencies of the signals.Therefore, it is necessary to have a stable modulation and demodulationcharacteristics.

Here, one of most important factors is a input dynamic range. The inputdynamic range indicates a range of a weakest input signal to a inputstrongest signal that can be stably received and demodulated.

For the wireless communication apparatus having the receiver andtransmitter circuits, the dynamic range is determined mainly byparameters such as transmission (high frequency) power, receptionsensitivity, and a distortion property.

There has been desire for a larger communication range. For a shortdistance communication (in which a distance between a host and a clientis short), one of conventional arts for attaining a large communicationrange is to prevent deterioration in distortion property with respect toa strong incoming signal by using an attenuator in an input stage of areceiver device, or by lowering a gain of a low-noise amplifier or an IFamplifier (see Reference 1: Japanese Publication of Utility Model,Jitsukaihei, No. 4-116440 (published on Oct. 29, 1992)) FIG. 22 shows anexample of the conventional art. In FIG. 22, an attenuator circuit (RFATT) 90 is provided in between a high frequency signal input terminal 71and a high frequency amplifier 78. The attenuator circuit (RF ATT) 90includes PIN diodes 91, 92, and 93. The PIN diodes 91, 92, and 93 can beused at RF-band.

In this example, the PIN diodes 91, 92, and 93 arranged in π-shape are(turned ON and OFF in accordance with a switching signal from a terminal77 depending on whether the high frequency signal is strong or weak.Thereby, the PIN diodes 91, 92, and 93 perform high frequencyattenuation when turned ON, whereas the PIN diodes 91, 92, and 93 are ina “through” state when turned OFF.

Note that in FIG. 22, there are provided a high frequency bandpassfilter (RFBPF) 79, a mixer (MIXER) 80, a first voltage-controlledoscillator (VCD1) 81, a first IF amplifier (IFAMP) 82, an IF bandpassfilter 83, a second IF amplifier 84, an FM detector (FMDET) 85, a secondvoltage controlling oscillator 86, and an output terminal 87 foroutputting a detected signal. Descriptions for these circuits areomitted, as they are well-known circuits. Further, in some cases, theattenuator circuit 90 in FIG. 22 is provided in between the highfrequency amplifier 78 and the RFBPF 79 or the mixer 80.

In the conventional art shown in FIG. 21, the power is supplied to thepower supply 64 of the card type wireless communication apparatus 50through the connector 65 from the information terminal device (notshown) such as a PC or the like. There will not be any problems as longas the information terminal device such as a PC or the like operateswith power from a commercial power source.

However, when the information terminal device such as a PC or the likeoperates in order to use the information terminal device such a PC orthe like in a mobile manner), the information terminal device isoperated with power supplied from a battery mounted in a main body ofthe information terminal device. Accordingly, the power supply 64 of thecard type wireless communication apparatus 50 is supplied, through theconnector 65, with the power from the battery mounted in the main bodyof the information terminal device such as a PC or the like.

Namely, an increase in the power consumption in the card type wirelesscommunication apparatus 50 causes a faster consumption of the batterymounted in the main body of the information terminal device. Thisshortens a time period (duration of battery) in which the informationterminal device can be used without the commercial power source.

SUMMARY OF THE INVENTION

In view of the foregoing problems, an object of the present invention isto provide a wireless communication circuit that allows both (a) anapparatus in which the circuit is provide, and (b) a counter apparatus(communication counterpart), to perform high-quality communication withlow power consumption, or to provide a card type wireless communicationcircuit in which a power consumption can be reduced by independentlycontrolling supplying and stopping actions of power to the respectivecircuits of the card type wireless communication apparatus, based on alevel of a received high frequency signal.

In order to achieve the foregoing object, a wireless communicationcircuit of the present invention, which includes an amplifier foramplifying a signal, is so arranged as to include: an amplificationroute in which the signal passes through the amplifier; a bypass routefor bypassing the amplifier; and a route-selector for selecting one ofthe amplification route and the bypass route.

With this arrangement, it is possible to select the route passing theamplifier or the bypass route, according to needs. For example, a bypassroute is selected when strength of the signal received is strong enough,because a communication counterpart is located in a close distance,whereas the route passing the amplifier is selected when the strength ofthe signal received is not strong enough, because the communicationcounterpart is located in a far distance.

In other words, a power is consumed for driving the amplifier whenselecting the route passing the amplifier, because the signal passes theamplifier. However, when the bypass route, bypassing the amplifier, isselected; the power is saved, because the amplifier does not have to bedriven.

This arrangement avoids unnecessary amplification of a signal that is tobe transmitted to a communication counter part in a close distance or asignal received from the communication counterpart in the closedistance, thereby reducing unnecessary power consumption.

Additional objects, features, and strengths of the present inventionwill be made clear by the description below. Further, the advantages ofthe present invention will be evident from the following explanation inreference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a card type wireless communicationapparatus of an embodiment according to the present invention, showing aspecific example of switching-over between a transmission poweramplifier and a bypass circuit.

FIG. 2 is a block circuit diagram schematically showing a configurationof the card type wireless communication apparatus.

FIG. 3 is a block diagram of the card type wireless communicationapparatus of another embodiment according to the present invention,showing a specific example of switching-over between a power amplifierand a fixed attenuator.

FIG. 4 is a block diagram of the card type wireless communicationapparatus of yet another embodiment according to the present invention,showing a specific example of switching-over between a power amplifierand a variable attenuator.

FIG. 5 is a block diagram of the card type wireless communicationapparatus of still another embodiment according to the presentinvention, showing a specific example of switching-over between alow-noise amplifier for reception, and a bypass circuit.

FIG. 6 is a block diagram of the card type wireless communicationapparatus of yet still another embodiment according to the presentinvention, showing a specific example of switching-over between alow-noise amplifier for reception, and a fixed attenuator.

FIG. 7 is a block diagram of the card type wireless communicationapparatus of still yet another embodiment according to the presentinvention, showing a specific example of switching-over between alow-noise amplifier for reception, and a variable attenuator.

FIGS. 8(a) to 8(f) are tables of simulation results, showing arelationship between communication ranges and provision of the poweramplifier for transmission.

FIGS. 9(a) to 9(f) are tables of the simulation results, showing arelationship between communication ranges and provision of the low-noiseamplifier for reception.

FIG. 10 is a flow chart showing how, in a transmission system, (a)switching-over between a power amplifier and a bypass route and (b)supply of power to the power amplifier, are controlled in accordancewith an RSSI value.

FIG. 11 is a flow chart showing how, in a transmission system, (a)switching-over between a power amplifier and a fixed attenuator, and (b)supply of power to the power amplifier, are controlled in accordancewith an RSSI value.

FIG. 12 is a flow chart showing how, in a transmission system, (a)switching-over between a power amplifier and a variable attenuator, (b)a switching-over of attenuation amount of the variable attenuator, and(c) supply of power to the power amplifier, are controlled in accordancewith an RSSI value.

FIG. 13 is a flow chart showing how, in a receiving end, (a)switching-over between a low-noise amplifier and a bypass route, and (b)supply of power to the low-noise amplifier, are controlled in accordancewith an RSSI value.

FIG. 14. is a flow chart showing how, in a receiving end, (a)switching-over between a low-noise amplifier and a fixed attenuator, and(b) supply of power to the low-noise amplifier, are controlled inaccordance with an RSSI value.

FIG. 15 is a flow chart showing how, in a receiving end, (a)switching-over between a low-noise amplifier and a variable attenuator,(b) switching-over of an attenuation amount of the variable attenuator,and (c) supply of power to the low-noise amplifier, are controlled inaccordance with an RSSI value.

FIG. 16. is an explanatory view showing an arrangement of a server and aclient, regarding communication protocol of wireless LAN.

FIG. 17 is an explanatory view showing various information to beinputted into a control means for allowing and stopping the supply ofpower to the low-noise amplifier and the power amplifier.

FIG. 18(a) is an explanatory view showing transmission and receptiontiming of coded date of a video signal.

FIG. 18(b) is an explanatory view showing transmission and receptiontiming of coded date of an audio signal.

FIG. 19 is an explanatory view showing relationship betweencommunication distance and attenuation of a transmission signal, theattenuation performed by the fixed attenuator or the variableattenuator.

FIG. 20 is a graph showing generation of a first control signal or asecond control signal in accordance with the RSSI value.

FIG. 21 is a block diagram schematically showing a configuration of aconventional card type wireless communication apparatus.

FIG. 22 is a block diagram showing a wireless module adopting agenerally-used RFAGC circuit.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described below withreference to FIGS. 1 to 10.

The following describes each of the embodiments with reference to thefigures.

FIG. 2 is a block circuit diagram of a circuit showing a configurationof a card type wireless communication apparatus, the configurationshared in all the embodiments. A circuit configuration in the card typewireless communication apparatus, from an antenna to a basebandprocessing LSI, is as follows.

The card type wireless communication apparatus has an antenna 1 forradiation a transmission signal to outside, and for picking up a signalfrom the outside. The antenna 1 is usually provided with an antenna anda diversity antenna, and is connected to a receiver circuit section(receiving system) and a transmitter circuit section (transmittingsystem) through a diversity switch (SW) 1 a and an RF band pass filter(BPF) 2, the diversity switch for switching the antenna and thediversity antenna.

After the RF band pass filter (BPF) 2 performs attenuation ofunnecessary frequency of a signal received by the antenna 1, thereceiver circuit section receives the signal (reception signal) during aperiod in which the transmitting/receiving switch (TX/RXSW) 3 switchesto the receiver circuit section. In the receiver circuit section, thereception signal is send to a low-noise amplifier (LNA) 4, by which thesignal is amplified. Then the reception signal is subjected to furtherattenuation by a low pass filter 5 or the like, whereby unnecessaryfrequency of the reception signal is attenuated. The reception signal isconverted (down convert) into an intermediate frequency (IF) by areception-use mixer 6, which is provided in an RF U/D converter. Thereception signal is subjected to band limitation by an IF filter 7, andto IQ demodulation by an IQ modem so as to be demodulated to I-signaland Q-signal. The I-signal and Q-signal are then respectively sent to abaseband processing circuit 8. Note that an RF frequency of thereception signal may be directly down-converted to a baseband frequency,instead of down-converting to the intermediate frequency (IF).

The signal (reproduction signal) thus regenerated by signal process inthe baseband processing circuit 8 is outputted from the basebandprocessing circuit 8 to an information terminal device, such as apersonal computer, a PDA or the like, in a form suitable for a type ofinterface circuit: PCMCIA (for card bus of 16-bit or 32-bit) for a PCcard, USB1.1 or USB2.0 for a USB adaptor, SDIO for a SD card, and so on.For an information terminal device in which the interface circuit isbuilt in, a PCI bus or the like is used for supplying the regeneratedsignal.

On the other hand, in the transmitter circuit, a data input signal inthe form suitable for the type of interface circuit (such aslater-described PCMCIA, USB or SDIO) is inputted into the basebandprocessing circuit 8 from the information terminal device such as thepersonal computer, the PDA (Personal Digital Assistance) or the like.Then the date input signal is subjected to the signal process by thebaseband processing circuit 8 and to IQ modulation by the IQ modem. Thedata input signal is then converted to the IF signal, and the IF signalis up converted (frequency conversion) by a transmission-use mixer 11,which is provided in the RF U/D converter. Then the signal thusmodulated is amplified by a power amplifier 9, so as to be atransmission signal, and the transmission signal flows backwards withrespect to the reception of signal and then is transmitted from theantenna 1.

In performing a normal communication, such card type wirelesscommunication apparatus is switched over between the transmission andreception alternatively in a short time period by transmitting/receivingswitch (TX/RXSW) 3, controlled by a controller (not shown).

Further, in the IQ modem, reception signal strength indicator (RSSI),which is a Direct-Current voltage, is generated by performing, by usinga diode or the like, envelope detection of the signal whose has beensubjected to band limitation by the IF filter 7. The RSSI is to beinputted to the baseband processing circuit 8 and used for generatingvarious controlling signals as described later.

Note that the receptor circuit section and the transmitter circuitsection are supplied with power from a power supply 40.

Embodiment 1

FIG. 1 is a block diagram showing a high frequency circuit section in awireless communication apparatus of an embodiment 1 according to thepresent invention; and a main part of the high frequency circuit sectionincludes a power amplifier 9, a bypass route 22, and route switches 23and 24 for a transmission signal.

The wireless communication apparatus of the present invention, which isa wireless communication apparatus for use in an information terminaldevice, includes an antenna 1; the power amplifier 9 for transmission,which is to be connected to the antenna 1 when it is selected; thebypass route 22 for bypassing a signal route (amplification route) ofthe power amplifier 9; and the route switches 23 and 24 (first switches)for selectively switching over between the signal route of the poweramplifier 9 and the bypass route 22.

The transmitter circuit section in the high frequency circuit has adetector diode 10. The detector diode 10, which is a schottky diode,performs demodulation (wave detection) of a transmission output signaland feeds back a direct-current component of the transmission outputsignal to a TX DET circuit (constituted of an operational amplifier orthe like), which is normally provided in a baseband processing circuit8. In accordance with the direct-current component, a gain of an AGCamplifier is automatically adjusted, thereby supplying stabletransmission power to an end of the antenna 1. This arrangementinvolving the detector diode 10 is well-known.

In the embodiment 1, as shown in FIG. 2, the baseband processing circuit8 has a control means (controller) 18 for controlling operation of thepower amplifier 9 and a low-noise amplifier 4 in accordance with theRSSI. The controller 18 controls the switching-over of the routeswitches 23 and 24 by a that property of signal which is indicative of adistance from a communication counterpart, such as strength of thereception signal (level of a high frequency input signal). In order toobtain such function, the controller 18 has a first control signalgenerating section 18 a for generating, in accordance with a voltage ofthe RSSI, an on/off control signal (a first control signal) that is usedfor the control of the route switches 23 and 24.

Note that the controller 18 (including a generating section 18 a) andswitches 23 and 24 for switching over the routes constitute aroute-selector for switching over between the amplifier route in whichthe signal passes through the low-noise amplifier 4 or the poweramplifier 9 (for selecting one of the low-noise amplifier 4 and thepower amplifier 9), and the bypass route for bypassing the low-noiseamplifier 4 or the power amplifier 9.

Moreover, by acquiring data for associating strength of the receptionsignal with communication distance, it is possible to convert thevoltage value of the RSSI into the communication distance. Thisarrangement may be attained by providing the controller 18 with, forexample, a detection section, a storage section (such as a look-up tableor the like), and a judgment section. The detection section detects(measures; takes reading of) the strength of the reception signal. Thestorage section stores the data for associating the strength of thereception signal with the communication distance. The judgment sectionjudges the communication distance in accordance with the date, thecommunication distance being in association with the strength thusmeasured. With this arrangement, it is possible to constitute thecontroller 18 to serve as a communication distance detector fordetecting (measuring) the distance to the communication counter part,and as the route-selector.

Further provided in embodiment 1 are the low-noise amplifier 4 and asecond switch 41. The second switch 41 is used for stopping supply ofpower to the power amplifier 9 from the power supply 40. The controller18 includes a control section 18 b for generating a second controlsignal, which is used for controlling the second switch 41 in accordanceto the switching-over of the route switches 23 and 24. The controller 18and the second switch 41 are used in the same manner in otherembodiments described later.

Note that the controller 18 (including a control section 18 b) and thesecond switch 41 constitute a power-supply stopper for stopping supplyof power to the low-noise amplifier 4 or the power amplifier 9, inaccordance with the switching-over to the bypass route.

The RSSI is, as shown in FIG. 20, generated as a DC voltage. It ispossible to generate the first control signal or the second controlsignal, by arranging such that the voltage value of the RSSI is comparedwith a threshold value for the voltage value of the RSSI (for example,the threshold value is set to 1.5V). For example, as shown in FIG. 20,if the voltage value of the RSSI is lower than the threshold value, itindicates that the strength of the reception signal is weak. Thus, alevel of the second control signal is turned to a high level, in orderto turn ON the power amplifier 9 or the low-noise amplifier 4. Moreover,if the voltage value of the RSSI is equal to or higher than thethreshold value, it indicates that the strength of the reception signalis strong. Thus, the level of the second control signal is turned to alow level, in order to turn OFF the power amplifier 9 or the low-noiseamplifier 4 so that the communication apparatus is turned to apower-saving mode.

Next, a operation process of the configuration in this embodiment isdescribed. In wireless communication, it is needless to say that, when asignal is wirelessly transmitted in a form of electric wave from a hostmachine (an apparatus such an access point, a router or the like; or atransmitting box or the like), strength of the signal thus transmittedand then received by a receiver circuit varies depending on a distancefrom the host machine. The wireless communication apparatus uses thereception signal strength indicator (RSSI) to show strength of theelectric wave thus received. For example, a mobile phone uses flags todisplay the strength of the input electric wave indicated by the RSSI.Three flags representing a strongest electric wave reception, and asingle flag or no flag for the weakest.

For example, such indicator is obtained by monitoring a DC voltage at aterminal called the RSSI which is provided in the baseband processingcircuit 8 shown in FIG. 2, and the indicator is digitally displayed forexample in three levels as described above in accordance withpredetermined values of the DC voltage.

In the case of the present invention, for example, two-levelswitching-over is carried out by using the voltage value of the RSSI(hereinafter, the voltage value of the RSSI is referred to as RSSIvalue). Operation of the control means (controller) 18 for thisarrangement is explained blew, referring to the flow chart of FIG. 10.

Firstly, the controller 18 monitors the direct current voltage (RSSIvalue) at the RSSI terminal of the baseband processing circuit 8. Whenthe controller 18 detects (measures) the RSSI value, the controller 18judges whether or not the RSSI value thus measured is lower than apredetermined level (Step (hereinafter, S) 1).

If an RSSI value is higher than a predetermined level, the controller 18judges that the host machine is in a close distance (S2). In such casethe bypass route 22 is selected by the route switches 23 and 24, whichare controlled by whether or not an on/off signal (PA_CTRL) is suppliedfrom the baseband processing circuit 8 (controlling system controller).Specifically, the controller 18 causes the generating section 18 a togenerate the first control signal (that is for controlling the switches23 and 24) (S3), the first control signal being for switching over fromthe signal route of the power amplifier 9 to the bypass route 22.

Here, the second switches 41 is turned OFF in accordance with theswitching-over of the route switches 23 and 24, so as to stop the supplyof the power to the power amplifier 9. In order to stop the supply ofthe power to the power amplifier 9, the controller 18 causes the controlsection 18 b to generate the second control signal that is for turningOFF the second switch 41 (S4).

On the other hand, if, at S1, the RSSI value thus measured is lower thanthe predetermined level, the controller 18 judges that the host machineis in a far distance (S5). In such case, to amplify the transmissionsignal by the power amplifier 9 before outputting the transmissionsignal, the route of the power amplifier is selected by the routeswitches 23 and 24, which are controlled by whether or not the on/offsignal (PA_CTRL) is supplied from the baseband processing circuit 8.Specifically, the controller 18 causes the generating section 18 a togenerate the first control signal that is for controlling the switches23 and 24, in order to switch over from the bypass route 22 to thesignal route of the power amplifier 9 (S6).

In this case, the second switch is turned ON in accordance with theswitching-over of the route switches 23 and 24, so that the poweramplifier 9 is supplied with the power and activated for amplificationof the signal. In order to supply the (allow the supply of the power),the controller 18 causes the control section 18 b to generate the secondcontrol signal that turns ON the second switch 41 (S7).

Note that the present embodiment may be so arranged that a user of thecommunication apparatus can switch over the switches 23 and 24, and turnON/OFF the second switch 41 manually and forcibly, the switches 23 and24, and the second switch 41 operating (switching over/turning ON/OFF)in concert. For example, this arrangement allows to select the bypassroute 22 manually in such a situation that the user prefers power-savingcommunication because a battery of the communication apparatus isrunning out.

With this arrangement, the communication can be so performed that thepower amplifier 9 of this embodiment is turned OFF when a communicationcounterpart (host machine or the like) is in a close distance. Thisdramatically reduces power consumption, thereby attaining “animprovement of a battery duration” and “an energy-saving design”.

Embodiment 2

FIG. 3 is a block diagram showing a high frequency circuit section in awireless communication apparatus of another embodiment according to thepresent invention. The high frequency circuit section in FIG. 3 ismodified from that of FIG. 1 as follows. A main part of the highfrequency circuit section includes a power amplifier 9 for transmission,and a fixed attenuator 22 a provided instead of the bypass route 22shown in FIG. 1, and route switches 23 and 24 for switching over routesfor a transmission signal. A detection diode 10 has the same function asthat of the embodiment 1.

Next described is an operation process of this configuration. Thiscard-type wireless communication apparatus performs two-levelswitching-over by using an RSSI value in accordance with a distance froma host machine (e.g. an apparatus such an access point, a router or thelike; or a transmitting box or the like). Operation of a controller 18for this case is explained blew, referring to the flow chart of FIG. 11.

Firstly, the controller 18 monitors a direct current voltage (RSSIvalue) at a RSSI terminal of a baseband processing circuit 8. When thecontroller 18 detects (measures) the RSSI value, the controller 18judges whether or not the RSSI value thus measured is lower than apredetermined level (S11).

If an RSSI value is equal to or higher than a predetermined level, thecontroller 18 judges that the host machine is perceived to be in a closedistance (S12). In such case a route passing the attenuator 22 a isselected by the route switches 23 and 24, which are controlled bywhether or not an on/off signal (PA_CTRL) is supplied from the basebandprocessing circuit 8. Specifically, the controller 18 causes agenerating section 18 a to generate a first control signal that is forcontrolling the switches 23 and 24 (S13),), the first control signalbeing for switching over from a signal route of a power amplifier 9 to aroute of the fixed attenuator 22 a.

Here, a second switch 41 is turned OFF in accordance with theswitching-over of the route switches 23 and 24, so as to stop supply ofpower to the power amplifier 9. In order to stop the supply of the powerto the power amplifier 9, the controller 18 causes a control section 18b to generate a second control signal that is for turning OFF the secondswitch 41 (S14).

On the other hand, if, at S11, the RSSI value thus measured is lowerthan the predetermined level, the controller 18 judges that the hostmachine is in a far distance (S15). In such case, to amplify atransmission signal by the power amplifier 9 before outputting thetransmission signal, a route passing the power amplifier is selected bythe route switches 23 and 24, which are controlled by whether or not anon/off signal (PA_CTRL) is supplied from the baseband processing circuit8. Specifically, the controller 18 causes the generating section 18 a togenerate the first control signal (that is for control the switches 23and 24) (S16), in order to switch over from the signal route of thefixed attenuator 22 a to the signal route of the power amplifier 9.

Here, the second switch is switched ON in accordance with theswitching-over of the route switches 23 and 24, so that the poweramplifier 9 is supplied with the power and activated for theamplification of the signal. In order to allow the supply of the power,the controller 18 causes the control section 18 b to generate the secondcontrol signal that is for turning ON the second switch 41 (S17).

Note that the present embodiment may be so arranged that a user of thecommunication apparatus can switch over the switches 23 and 24, and turnON/OFF the second switch 41 manually and forcibly, the switches 23 and24, and the second switch 41 operating (switching over/turning ON/OFF)in concert. For example, this arrangement allows to select the signalroute of the fixed attenuator 22 a manually in such a situation that theuser prefers power-saving communication because a battery of thecommunication apparatus is running out.

This embodiment 2 is so arranged that the power amplifier 9 fortransmission, the fixed attenuator 22 a, and the route switches 23 and24 for controlling the respective ON/OFF states of the power amplifier 9and the fixed attenuator 22 a are provided in a high frequencyamplification stage of a transmitter circuit block, and the routeswitches 23 and 24 are used for selecting one of the power amplifier 9and the fixed attenuator 22 a by switching over in accordance with alevel of the high frequency input signal (RSSI) inputted into areception block, the level varied depending on a distance from acommunication counterpart, such as the host machine (e.g. an apparatussuch an access point, a router or the like; or a transmitting box or thelike). In this arrangement, the selected one of the power amplifier 9and the fixed attenuator 22 a becomes part of a close circuit.

Thus, this embodiment brings about the same effects of the embodiment 1;that is, “an improvement of a battery duration” and “energy-savingdesign”. Further in a case that the route passing the fixed attenuator22 a is automatically selected for communication with the host machinein the close distance, the wireless communication apparatus in thisembodiment further reduces a level of disturbance to a communicationequipment (other than the wireless communication apparatus of thisinvention and the host machine thereof) which uses the same frequencyband as the wireless communication apparatus of this invention and thehost machine thereof, compared to embodiment 1 in which the bypass route22 is used.

This becomes very important, particularly when applying this inventionto a wireless LAN or the like that is in compliance with IEEE802.11b.IEEE802.11b is a standard using a frequency included in 2.4 GHz-band.Because various fields such as industry, science, and medical sciencecan freely use this frequency included in 2.4 GHz-band, variousapparatuses such as bluetooth-using devices, microwave ovens, POSterminals, and security cameras are emitting electronic waves of thisfrequency band. Under such circumstance, a suppression of an electricwave emission level is etiquette, and is an important function.

Further, in case where the RSSI value is higher than a predeterminedlevel, that is, for the communication distance shorter than apredetermined value, the fixed attenuator 22 a is selected so as toreduce a current value of a transmission signal. Therefore, comparedwith the arrangement shown in FIG. 1, in which the fixed attenuator 22 ais not provided, the arrangement of the present embodiment further savespower consumption from the battery.

Moreover, in the following condition, the present embodiment is moreadvantageous in terms of the power consumption from the battery,compared with an arrangement in which, as in a next-described embodiment3, a variable attenuator 22 b is used instead of the fixed attenuator 22a so that the current value of the transmission signal is reduced(adjusted) stepwise in accordance with the communication distance. Thecondition is that, as shown in FIG. 19, a communication range (distanceD1 to D2) is wider than a communication range (distance D2 to D3), wherea communication range (distance D1 to D2) is a communication rangewithin which a current value I (fixed) obtained by using the fixedattenuator 22 a is smaller than a current value I (variable) obtained byusing the variable attenuator 22 b, whereas distance D2 to D3 is acommunication range within which the current value I (variable) issmaller than the current value I (fixed) in case where the current valueof the transmission signal is reduced to a predetermined value I0 forperforming communication of a certain communication distance.

Embodiment 3

FIG. 4 is a block diagram showing a high frequency circuit section in awireless communication apparatus of yet another embodiment according tothe present invention. The high frequency circuit section in FIG. 4 ismodified from the arrangement of FIG. 1 as follows. A main part of thehigh frequency circuit section includes a power amplifier 9 fortransmission, and a variable attenuator 22 b provided instead of thebypass route 22 shown in FIG. 1, and switches 23 and 24 for switchingover routes for a transmission signal. A role of a detection diode 10 isthe same as the previous description.

Next described is an operation process of this configuration. By usingan RSSI value, the card-type wireless communication apparatus performssuch switching-over that attenuation amount can be delicately adjustedaccording to a distance from a host machine (e.g. an apparatus such anaccess point, a router or the like; or a transmitting box or the like).Operation of a controller 18 for this arrangement is explained blew,referring to the flow chart of FIG. 12.

Firstly, the controller 18 monitors the direct current voltage (RSSIvalue) at an RSSI terminal of a baseband processing circuit 8. When thecontroller 18 detects (measures) the RSSI value, the controller 18judges whether or not the RSSI value thus measured is lower than apredetermined level 1 (S21).

If an RSSI value is higher than the predetermined level 1, thecontroller 18 judges that the host machine is in a close distance (S22).In such case, a route passing the variable attenuator 22 b is selectedby the route switches 23 and 24, which are controlled by whether or notan on/off signal (PA_CTRL) is supplied from the baseband processingcircuit 8. Specifically, the controller 18 causes a generating section18 a to generate a first control signal that is for controlling theswitches 23 and 24 (S23), in order to switch over from a signal route ofa power amplifier 9 to a signal route of the variable attenuator 22 b.

Here, supply of power to the power amplifier 9 is stopped by the secondswitch 41, which is turned OFF in accordance with the switching-over ofthe switches 23 and 24. In order to stop the supply of the power to thepower amplifier 9, the controller 18 causes a control section 18 b togenerate a second control signal that is for turning OFF the secondswitch 41 (S24).

After that, the baseband processing circuit 8 divides an attenuationamount into a number of levels in accordance with a resolution abilityof an D/A converter (of 4 bits, for example) in accordance with a levelof an electric wave, which depends on a distance (communicationdistance) from the host machine. For example, if using 4-bit D/Aconverter, and 40 dB is a total amount that can be attenuated, theattenuation amount per level is 2.5 dB.

For example, the controller 18 judges whether or not the RSSI value thusmeasured is lower than a predetermined level 2, which is higher than thepredetermined level 1 (S25). If the RSSI value thus measured is equal toor higher than the predetermined value 2, the controller 18 furtherjudges whether the RSSI value thus measured is lower than apredetermined value 3, which is higher than a predetermined value 2(S26). Here, assuming that the predetermined value 3 is the highestamong the multileveled threshold values, the controller 18 sets theattenuation amount of the variable attenuator 22 b to an attenuationlevel 3 (maximum attenuation amount) by using an D/A converter, if theRSSI value is equal to or higher than the predetermined level 3 (S27).

On the other hand, if, at S25, the RSSI value thus measured is less thanthe predetermined level 2, the attenuation amount of the variableattenuator 22 b is set to an attenuation level 1 (minimum attenuationamount) that corresponds to the predetermined level 1 (S28). Further,if, at S26, the RSSI value thus measured is less than the predeterminedlevel 3, the attenuation amount of the variable attenuator 22 b is setto an attenuation level 2 that corresponds to the predetermined level 2(S29).

Note that the predetermined levels 1 to 3, to be compared with the RSSIvalue, and the attenuation levels 1 to 3, which respectively correspondto the predetermined levels 1 to 3, are stored in a memory (such as alook-up table or the like), which the controller 18 can access.

On the other hand, if, at S21, the RSSI value is lower than thepredetermined level 1, the controller 18 judges that the host machine isin a far distance (S30). In such case, to amplify a transmission signalby the power amplifier 9 before outputting the transmission signal, theroute passing the power amplifier 9 is selected by the route switches 23and 24, which are controlled by whether or not an on/off signal(PA_CTRL) is supplied from the baseband processing circuit 8.Specifically, the controller 18 causes a generating section 18 a togenerate a first control signal that is for controlling the switches 23and 24 (S31), in order to switch over from a signal route of thevariable attenuator 22 b to a signal rote of the power amplifier 9.

Here, the second switch is turned ON in accordance with theswitching-over of the route switches 23 and 24, so that the poweramplifier 9 is supplied with the power and activated for theamplification of the signal. In order to allow the supply of the powerto the power amplifier 9, the controller 18 causes a control section 18b to generate a second control signal that is for turning ON the secondswitch 41 (S32).

Note that the present embodiment may be so arranged that a user of thecommunication apparatus can switch over the switches 23 and 24, and turnON/OFF the second switch 41 manually and forcibly, the switches 23 and24, and the second switch 41 operating (switching over/turning ON/OFF)in concert. For example, this arrangement allows to select the signalroute of the variable attenuator 22 b in such a situation that the userprefers power-saving communication because a battery of thecommunication apparatus is running out.

This embodiment 3 is so arranged that the power amplifier 9 fortransmission, the variable attenuator 22 b, and the route switches 23and 24 for controlling the power amplifier 9 and the variable attenuator22 b are provided in a high frequency amplification stage of atransmitter circuit block, and the route switches 23 and 24 are used forselecting one of the route passing the power amplifier 9, and the routepassing the variable attenuator 22 b by switching over in accordancewith a level of the high frequency input signal (RSSI) inputted into areception block, the level varied depending on the distance from acommunication counterpart, such as the host machine (e.g. an apparatussuch an access point, a router or the like; or a transmitting box or thelike). In this arrangement, the selected one of the power amplifier 9and the variable attenuator 22 b becomes part of a close circuit.

Thus, this embodiment brings about the same effects of the embodiment 1;that is, “an improvement of a battery duration” and “energy-savingdesign”. Further, in a case that the route passing the variableattenuator 22 b is automatically selected for communication with thehost machine in the close distance, the wireless communication apparatusin this embodiment further reduces a level of disturbance to acommunication equipment (other than the wireless communication apparatusof this invention and the host machine thereof) which uses the samefrequency band as the wireless communication apparatus of this inventionand the host machine thereof, compared to a case of using the bypassroute 22 described in embodiment 1.

Further, in case of embodiment 2 in which the fixed attenuator 22 a isused, it should not be so arranged that the fixed attenuator 22 a has alarge attenuation amount, on the grounds that such large attenuationamount possibly shortens a communication range. However, the variableattenuator 22 b can varies the attenuation amount in accordance with thelevel of the high frequency input signal (RSSI), so that thecommunication can be carried out with a largest affordable attenuationamount that the communication can afford (the largest affordableattenuation amount is an attenuation amount at which communication canbe performed while minimizing adverse effect on external devices (otherdevices)). This brings about more effective suppression of a level of anelectric wave radiation that disturbs external apparatuses, comparedwith the embodiment 2.

If the strength of the transmission signal was unnecessarily large(larger than a necessary strength), possibility would be higher that thetransmission signal adversely affects electronic devices, especially,the electronic devices using a frequency near the frequency band of thecommunication apparatus, and electronic devices using a receptionfrequency near a frequency band of a high frequency wave component of aninterference wave, and the like electronic apparatus. Therefore, byselecting, in accordance with the level of the RSSI value, a mostsuitable attenuation rate for communication state or communicationdistance of a moment, a radiation level of the interfering electronicwave, which adversely affects the electronic devices in the surrounding,can be reduced to a most appropriate level of the moment, withoutscarifying the communication state or the communication distance. As aresult, it is possible to minimize the possibility that the transmissionsignal adversely affects the electronic devices and the like.

Embodiment 4

FIG. 5 is a block diagram showing an high frequency circuit section in awireless communication apparatus of still another embodiment accordingto the present invention. The high frequency circuit section in FIG. 5is modified from that of FIG. 1 as follows. A main part of the highfrequency circuit includes a low-noise amplifier (LNA) 4 for reception,and a bypass route 32, route switches 33 and 34 (first switches) forswitching over routes of a reception signal.

Therefore, a wireless communication circuit according to the presentinvention, which is a wireless communication circuit for use ininformation transmission and reception terminal (device), is so arrangedas to be provided with: an antenna 1; a low-noise amplifier 4, whichserves as an amplifier to be connected with the antenna 1; a bypassroute 32 for bypassing a signal route of the low-noise amplifier 4; andswitches (first switches) 33 and 34 for alternatively switching over thesignal route of the low-noise amplifier 4 and the bypass route 32. Notethat, a second switch 42 is provide between the low-noise amplifier 4and a power supply 40 for supplying power to the low-noise amplifier 4.The second switch 42 turns ON and OFF in accordance with a secondcontrol signal generated by a control section 18 b.

Like the switches 23 and 24 in the embodiment 1, the route switches 33and 34 switch over according to whether or not a control (ON/OFF) signalis supplied from a controller 18 to the route switches 33 and 34.Further, power to the low-noise amplifier 4 is supplied and stopped bythe second switch 42 in accordance with the switching-over of theswitches 33 and 34.

Next described is an operation process of this configuration. Thiscard-type wireless communication apparatus performs two-levelswitching-over, by using an RSSI voltage, in accordance with a distancefrom a host machine (e.g. an apparatus such an access point, a router orthe like; or a transmitting box or the like). The route switches 33 and34 are initially set to select a route passing the low-noise amplifier4. Operation of a controller 18 for this arrangement is explained blew,referring to the flow chart of FIG. 13.

Firstly, the switches 33 and 34 are initially switched over to thelow-noise amplifier 4. This is because initial reception of the signalcan be more smoothly performed if it is so set that the communicationmode is switched over from a normal mode (in which the power issupplied) to a power-saving mode (in which the bypass route 32 isselected) according to communication state, than if it is so set thatthe communication mode is switched over from the power-saving mode tothe normal mode.

Next, the controller 18 monitors the direct current voltage (RSSI value)at the RSSI terminal of the baseband processing circuit 8. When thecontroller 18 detects (measures) the RSSI value, the controller 18judges whether or not the RSSI value thus measured is lower than apredetermined level (S41).

If an RSSI value is higher than a predetermined level at a moment when alinkage to the host machine is established, the controller 18 judgesthat the host machine is in a close distance (S42). In such case thebypass route 32 is selected by the route switches 33 and 34, which arecontrolled by whether or not an LNA_CTRL signal is supplied from thebaseband processing circuit 8. Specifically, the controller 18 causes agenerating section 18 a to generate a first signal that is forcontrolling the route switches 33 and 34 (S43), in order to switch overfrom the route of the low-noise amplifier 4 to the bypass route 32.

Here, the second switch 42 is turned OFF, in accordance with theswitching-over of the route switches 33 and 34, so as to stop the supplyof the power to the low-noise amplifier 4. In order to stop the supplyof the power to the low-noise amplifier 4, the controller 18 causes thecontrol section 18 b to generate a second control signal that is forturning OFF the second switch 42 (S44).

On the other hand, if, at S41, the RSSI value is lower than thepredetermined level, the controller 18 judges that the host machine isin a far distance (S45). In such case, according to whether or not theLNA_CTRL signal is supplied from the baseband processing circuit 8 tothe switches 33 and 34, the switches 33 and 34 are switched to thelow-noise amplifier 4 so that a signal is amplified by the low-noiseamplifier 4 and then sent to a LPF 5, which is a next stage receptorcircuit. Specifically, the controller 18 causes the generating section18 a to generate the first signal that is for controlling the switches33 and 34 (S46), in order to switch over from the bypass route 32 to theroute of the low-noise amplifier 4.

Here, the second switch 42 is turned ON in accordance with theswitching-over of the switches 33 and 34 so that the low-noise amplifier4 is supplied with power and activated for the amplification of thesignal. In order to allow the supply of the power to the low-noiseamplifier 4, the controller 18 causes the control section 18 b togenerate the second control signal that turns ON the second switch 42(S47).

Note that the present embodiment may be so arranged that theswitching-over of the switches 33 and 34, and the turning ON/OFF of thesecond switch 42 can be manually switched over/turned ON/OFF forcibly bya user of the communication apparatus, the switching-over of theswitches 33 and 34, and the turning ON/OFF of the second switch 42operating in concert. For example, this arrangement allows to select thebypass route 32 in such a situation that the user prefers power-savingcommunication because a battery of the communication apparatus isrunning out.

This embodiment 4 is so arranged that the low-noise amplifier 4 forreception, the bypass route 32, and the switches 33 and 34 forcontrolling the low-noise amplifier 4 and the bypass route 32 areprovided in a high frequency amplification stage of a receptor circuitblock, and the switches 33 and 34 are used for selecting one of thelow-noise amplifier 4 and bypass route 22 by switching over inaccordance with a level of the high frequency input signal (RSSI)inputted to the reception block, the level varied depending on thedistance from the host machine (e.g. an apparatus such an access point,a router or the like; or a transmitting box or the like). In thisarrangement, the selected one of the low-noise amplifier 4 and bypassroute 22 becomes part of a close circuit.

With this arrangement, when the bypass route 32 is selected, the powerconsumption is reduced as much as the power saved by not using thegenerally-used low-noise amplifier 4. In a current wireless LAN card incompliance with IEEE802.11b, for example, the low-noise amplifier 4consumes a twentieth of an entire power consumption within the wirelessLAN card.

Therefore, if the distance from the host machine is so nearer than thethreshold (the predetermined level), the power consumption is lower thanthe conventional art. This brings about an energy-saving design, andattains that a mobile information terminal device (a notebook-type PC, aPDA, a portable telephone, or the like) or the like device adopting thewireless communication apparatus (client) of this invention can performbattery-driven communication for a longer time. As for a setting of thethreshold, it is described later.

Embodiment 5

FIG. 6 is a block diagram showing a high frequency circuit section in awireless communication apparatus of yet still another embodimentaccording to the present invention. The high frequency circuit sectionin FIG. 6 is modified from that of FIG. 5 as follows. A main part of thehigh frequency circuit section includes a low-noise amplifier 4 fortransmission, a fixed attenuator 32 a (in replacement of the bypassroute 32 shown in FIG. 5), and route switches 33 and 34 for switchingover routes for a reception signal. Note that a second switch 42 isprovided between the low-noise amplifier 4 and a power supply 40 forsupplying power to the low-noise amplifier 4. The second switch 42 turnsON and OFF in accordance with a second control signal generated by acontrol section 18 b.

Next described is an operation process of this configuration. Thiscard-type wireless communication apparatus performs two-levelswitching-over by using an RSSI voltage in accordance with a distancefrom a host machine (e.g. an apparatus such an access point, a router orthe like; or a transmitting box or the like). Operation of a controller18 for this arrangement is explained blew, referring to the flow chartof FIG. 14.

Firstly, the route switches 33 and 34 are initially set to select aroute passing the low-noise amplifier 4. Next, the controller 18monitors the direct current voltage (RSSI value) at the RSSI terminal ofthe baseband processing circuit 8. When the controller 18 detects(measures) the RSSI value, the controller 18 judges whether or not theRSSI value thus measured is lower than a predetermined level (S51).

If an RSSI value is higher than a predetermined level at a moment when alinkage to the host machine is established, the controller 18 judgesthat the host machine is in a close distance (S52). In such case, theroute passing the fixed attenuator 32 a is selected by the routeswitches 33 and 34, which are controlled by whether an LNA_CTRL signalis supplied from the baseband processing circuit 8. Specifically, thecontroller 18 causes a generating section 18 a to generate a firstsignal that is for controlling the switches 33 and 34 (S53), in order toswitch over from a signal route of the low-noise amplifier 4 to a signalroute of the a fixed attenuator 32 a.

Here, the second switch 42, in accordance with the operation of theswitches 33 and 34, is switched OFF so as to stop supply of power to thelow-noise amplifier 4. In order to stop the supply of the power to thelow-noise amplifier 4, the controller 18 causes the control section 18 bto generate the second control signal that is for turning OFF the secondswitch 42 (S54).

On the other hand, if, at S51, the RSSI value thus measured is lowerthan the predetermined level, the controller 18 judges that the hostmachine is in a far distance (S55). In such case, according to whetherthe LNA_CTRL signal is supplied from the baseband processing circuit 8,the switches 33 and 34 are switched to the low-noise amplifier 4 so thata signal is amplified by the low-noise amplifier 4 and then sent to aLPF 5, which is a next stage receptor circuit. Specifically, thecontroller 18 causes the generating section 18 b to generate the firstcontrol signal that is for controlling the switches 33 and 34 (S56), inorder to switch over from the signal route of the fixed attenuator 32 ato the signal route of the low-noise amplifier 4.

Here, the second switch 42 is turned ON in accordance with theswitching-over of the switches 33 and 34 so that the low-noise amplifier4 is supplied with power from the power supply and is activated for theamplification of the signal. In order to allow the supply of the powerto the low-noise amplifier 4, the controller 18 causes the controlsection 18 b to generate the second control signal that turns ON thesecond switch 42 (S57).

Note that the present embodiment may be so arranged that theswitching-over of the switches 33 and 34, and the turning ON/OFF of thesecond switch 42 can be manually switched over/turned ON/OFF forcibly bya user of the communication apparatus, the switching-over of theswitches 33 and 34, and the turning ON/OFF of the second switch 42operating in concert. For example, this arrangement allows to select thesignal route of the fixed attenuator 32 a in such a situation that theuser prefers power-saving communication because a battery of thecommunication apparatus is running out.

The invention described in this embodiment 5 is so arranged that thelow-noise amplifier 4 for reception, the fixed attenuator 32 a, and theroute switches 33 and 34 for controlling the low-noise amplifier 4 andthe route passing the fixed attenuator 32 a are provided in a highfrequency amplification stage of a receptor circuit block, and the routeswitches 33 and 34 are used for selecting one of the low-noise amplifier4 and the route passing the fixed attenuator 32 a by switching over inaccordance with a level of the high frequency input signal (RSSI)inputted into a reception block, the level varied depending on thedistance from a communication counterpart, such as the host machine(e.g. an apparatus such an access point, a router or the like; or atransmitting box or the like). The selected one of the low-noiseamplifier 4 and the fixed attenuator 32 a becomes part of a closecircuit.

Thus, this embodiment brings about the same effects of the embodiment 4;that is, “an improvement of a battery duration” and “energy-savingdesign”. Further, this embodiment attains the following effect: When thedistance between the communication apparatus and the host machine issufficiently close so that the fixed attenuator 32 a is automaticallyselected, if the distance was excessively close, a distortion propertywould be deteriorated thereby deteriorating reception sensitivity. Withthis arrangement of embodiment 5, it is possible to perform thecommunication in a closer distance (range), because an attenuationamount of the fixed attenuator 32 a improves the distortion property.

Reception sensitivity of the communication apparatus is deterioratedwhen the distance between the communication apparatus and the hostmachine. This is because, due to characteristic of a transistor and adiode which they use, distortion factor in the switch (TX/RXSW) 3, thelow-noise amplifier 4, the U/D converter, and the like is deterioratedwhen a strength of an input is excessively large.

Embodiment 6

FIG. 7 is a block diagram showing a high frequency circuit section in awireless communication apparatus of still yet another embodimentaccording to the present invention. The high frequency circuit sectionin FIG. 7 is modified from that of FIG. 5 as follows. A main part of thehigh frequency circuit section includes a low-noise amplifier 4 fortransmission, and a variable attenuator 32 b (provided instead of abypass route 32 shown in FIG. 5), and route switches 33 and 34 forswitching over routes of a reception signal. Note that a second switch42 is provided between the low-noise amplifier 4, and a power supply 40for supplying power to the low-noise amplifier 4. The second switch 42turns ON and OFF in accordance with a second control signal generated bya control section 18 b.

Next described is an operation process of this configuration. Thecard-type wireless communication apparatus performs delicateswitching-over by using an RSSI voltage in accordance with a distancefrom a host machine (e.g. an apparatus such an access point, a router orthe like; or a transmitting box or the like). Operation of a controller18 for this arrangement is explained blew, referring to the flow chartof FIG. 15.

Firstly, the controller 18 monitors the direct current voltage (RSSIvalue) at the RSSI terminal of the baseband processing circuit 8. Whenthe controller 18 detects (measures) the RSSI value, the controller 18judges whether or not the RSSI value thus measured is lower than apredetermined level (S61).

If an RSSI value is higher than a predetermined level 1, the controller18 judges that the host machine is in a close distance (S62). In suchcase the variable attenuator 32 b is selected by the route switches 33and 34, which are controlled by whether or not an LNA_CTRL signal issupplied from the baseband processing circuit 8. Specifically, thecontroller 18 causes a generating section 18 a to generate a firstcontrol signal that is for controlling the switches 33 and 34, in orderto switch over from a signal route of the amplifier 4 to a signal routeof a variable attenuator 32 b (S63).

Here, the second switch 42 is turned OFF in accordance with theswitching-over of the route switches 33 and 34, so as to stop supply ofpower to the low-noise amplifier 4. In order to stop the supply of thesupply of the power to the low-noise amplifier 4, the controller 18causes the controller 18 b to generate the second control signal thatturns OFF the second switch 42 (S64).

Next, by using the base band processing circuit 8, it is adjusted suchthat the attenuation amount is divided into levels according to a limitof resolution of a D/A converter (which is of 4 bit for example),depending on a level of the electric wave that changes according to thedistance from the host machine. (For example, if using 4-bit D/Aconverter, and 40 dB is a total amount that can be attenuated, theattenuation amount per level is 2.5 dB).

For example, the controller 18 judges whether or not the RSSI value thusmeasured is lower than a predetermined level 2, which is higher than thepredetermined level 1 (S65). If the RSSI value thus measured is equal toor higher than the predetermined value 2, the controller 18 furtherjudges whether the RSSI value thus measured is lower than apredetermined value 3, which is higher than a predetermined value 2(S66). Here, assuming that the predetermined value 3 is the highestamong the multileveled threshold values, the controller 18 sets theattenuation amount of the variable attenuator 22 b to an attenuationlevel 3 (maximum attenuation amount) by using an D/A converter, if theRSSI value is equal to or higher than the predetermined level 3 (S67).

On the other hand, if, at S65, the RSSI value thus measured is less thanthe predetermined level 2, the attenuation amount of the variableattenuator 22 b is set to an attenuation level (minimum attenuationamount) that corresponds to the predetermined level 1 (S68). Further,if, at S66, the RSSI value thus measured is less than the predeterminedlevel 3, the attenuation amount of the variable attenuator 22 b is setto an attenuation level 2 that corresponds to the predetermined level 2(S69).

Note that the predetermined levels 1 to 3 to be compared with the RSSIvalue, and the attenuation levels 1 to 3, which respectively correspondto the predetermined levels 1 to 3, are stored in a memory (such as alook-up table or the like), which the controller 18 can access.

On the other hand, if, at S61, the RSSI value is lower than thepredetermined level 1, the controller 18 judges that the host machine isin a far distance (S70). In such case, to amplify the signal by thelow-noise amplifier 4 before sending the signal to a LPF 5, which is anext-stage receiver circuit, the low-noise amplifier 4 is selected bythe route switches 33 and 34, according to whether or not the LNA_CTRLsignal is supplied from the baseband processing circuit 8. Specifically,the controller 18 causes a generating section 18 a to generate a firstcontrol signal that is for controlling the switches 33 and 34 (S71), inorder to switch over from a signal route of the variable attenuator 32 bto a signal route of the low-noise amplifier 4.

Here, the second switch is switched ON in accordance with theswitching-over of the route switches 33 and 34, so that the low-noiseamplifier 4 is supplied with power and is activated for theamplification of the signal. In order to allow the supply of the powerto the low-pass amplifier 4, the controller 18 causes the controlsection 18 b to generate the second control signal that turns ON thesecond switch 42 (S72).

Note that the present embodiment may be so arranged that a user of thecommunication apparatus can switch over the switches 23 and 24, and turnON/OFF the second switch 41 manually and forcibly, the switches 23 and24, and the second switch 41 operating (switching over/turning ON/OFF)in concert. For example, this arrangement allows to select the signalroute of the variable attenuator 32 b in such a situation that the userprefers power-saving communication because a battery of thecommunication apparatus is running out.

This embodiment 6 is so arranged that the low-noise amplifier 4 forreception, the variable attenuator 32 b, and the route switches 33 and34 for switching over the low-noise amplifier 4 and the variableattenuator 32 b are provided in a high frequency amplification stage, ofa receptor circuit block, and the route switches 33 and 34 is used forselecting one of the low-noise amplifier 4 and the variable attenuator32 b, by switching over in accordance with a level of the high frequencyinput signal (RSSI) inputted into a reception block, the level varieddepending on the distance from a communication counterpart, such as thehost machine (e.g. an apparatus such an access point, a router or thelike; or a transmitting box or the like). In this arrangement, theselected one of the low-noise amplifier 4 and the variable attenuator 32b becomes part of a close circuit.

Thus, this embodiment brings about the same effects of the embodiment 4;that is, “an improvement of a battery duration” and “energy-savingdesign”. Further, this embodiment attains the following effect: When thedistance from the host machine is sufficiently close so that thevariable attenuator 32 b is automatically selected, if the distance wasexcessively close, a distortion property would be deteriorated therebydeteriorating reception sensitivity. With this arrangement of embodiment5, it is possible to perform the communication in a closer distance(range) more flexibly and more conveniently than the invention ofembodiment 5, because an attenuation amount of the variable attenuator32 b is varied (adjusted) in accordance with the level of the highfrequency input signal (RSSI).

For example, the use of the variable attenuator 32 b allows finer modeselection (high attenuation amount/medium attenuation amount/lowattenuation amount/no attenuation amount/switching-over to the low-noiseamplifier) than two-mode selection (attenuation (1)/no attenuation (0)).Therefore, even if the level of the high-frequency input signal (RSSI)is abruptly changed, it is possible to adjust the reception sensitivityto its more optimum sensitivity suitable for a communication distance ofa moment, compared with the two-mode selection. In the two-modeselection, attenuation amount would be inevitably reduced to 0 in caseof abrupt change in the level of the high frequency input signal (RSSI)(for example, in case where the optimum attenuation amount was changedto 30 dB to 20 dB when communication is performed with a communicationdistance which requires an attenuation amount of 30 dB under ordinarycircumstances, attenuation amount would be inevitably reduced to 0 inthe two-mode selection in which attenuation of 30 dB or no attenuationis selected). As a result, the communication distance between thecommunication apparatus and the host machine would be too “short”. Thisleads to deterioration of the reception sensitivity due to distortion,and increases in occurrence of reception errors.

On the other hand, the use of the variable attenuator 32 b allows to setthe attenuation amount to its optimum amount suitable for thecommunication state and communication distance of the moment, therebymaking it possible to suppress the deterioration of the receptionsensitivity and the increase in the occurrence of the reception errors.

Because of the use of the variable attenuator 32 b, this embodiment 6 iseffective, particularly to a device such as a PDA, a mobile phone andthe like, which may be used for communication in which the distance fromthe host machine constantly changes.

A wireless communication apparatus of the present invention, which is acard-type wireless communication apparatus to be connected with aninformation terminal device or built-in type module to be built in aninformation terminal device, includes: (i) an antenna; (ii) a receivercircuit section for demodulating a high frequency signal received by theantenna and converting a frequency of the high frequency signal, and foroutputting a baseband receiving signal; (iii) a transmitter circuitsection for modulating a baseband transmission signal and converting afrequency of the baseband transmission signal, and for outputting thehigh frequency signal to the antenna; (iv) a baseband signal processingcircuit section for conducting a signal processing to the basebandtransmission signal and the baseband receiving signal; (v) an interfacecircuit section having an interface function with an informationterminal device; (vi) a power supply for supplying power to each of thecircuit sections; and (vii) a connector for connecting with theinformation terminal device.

The wireless communication apparatus according to the present inventionis further arranged such that a high frequency amplification stage of atransmitter circuit block includes a transmission power amplifier, abypass circuit, a switching circuit for selecting the transmission poweramplifier and a bypass circuit, the switching circuit being switchedover in accordance with a level of the high frequency input signalinputted into the reception block, so as to form a close circuit withthe power amplifier or the bypass circuit selectively, the level of thehigh frequency input signal depending on a distance from a host machine(an apparatus such an access point, a router or the like; or atransmitting box or the like).

The wireless communication apparatus may be so arranged that a highfrequency amplification circuit stage of a transmitter circuit block has(i) a power amplifier for transmitting; (ii) a fixed attenuator; and(iii) a switching circuit for selecting one of the route passing thepower amplifier and a route passing the fixed attenuator, the switchingcircuit being switched over in accordance with a level of the highfrequency input signal inputted into the reception block, so as to forma close circuit with the power amplifier or the fixed attenuatorselectively, the level of the high frequency input signal depending on adistance from a host machine (an apparatus such an access point, arouter or the like; or a transmitting box or the like).

The wireless communication apparatus may be so arranged that a highfrequency amplification stage of the transmitter circuit block has (i)the power amplifier for transmitting; (ii) a variable attenuator; and(iii) the switching circuit for selecting the power amplifier and aroute passing the variable attenuator, the switching circuit beingswitched over in accordance with a level of the high frequency inputsignal inputted into the reception block, so as to form a close circuitwith the power amplifier or the variable attenuator selectively, thelevel of the high frequency input signal depending on a distance from ahost machine (an apparatus such an access point, a router or the like;or a transmitting box or the like).

The wireless communication apparatus may be so arranged that a highfrequency amplification stage of the receptor circuit block has (i) alow-noise amplifier; (ii) the bypass route; and (iii) the switchingcircuit for selecting one of the route passing the power amplifier andthe bypass route, the switching circuit being switched over inaccordance with a level of the high frequency input signal inputted intothe reception block, so as to form a close circuit with the bypass routeor the low-noise amplifier selectively, the level of the high frequencyinput signal depending on a distance from a host machine (an apparatussuch an access point, a router or the like; or a transmitting box or thelike).

The wireless communication apparatus may be so arranged that a highfrequency amplification stage of the receptor circuit block has (i) alow-noise amplifier; (ii) a fixed attenuator; and (iii) the switchingcircuit for selecting one of the route passing the power amplifier andthe route passing the fixed attenuator, the switching circuit beingswitched over in accordance with a level of the high frequency inputsignal inputted into the reception block, so as to form a close circuitwith the low-noise amplifier or a fixed attenuator selectively, thelevel of the high frequency input signal depending on a distance from ahost machine (an apparatus such an access point, a router or the like;or a transmitting box or the like).

The wireless communication apparatus may be so arranged that a highfrequency amplification stage of the receptor circuit block has (i) alow-noise amplifier; (ii) a variable attenuator; and (iii) the switchingcircuit for selecting one of the route passing the power amplifier andthe route passing the fixed attenuator, the switching circuit beingswitched over in accordance with a level of the high frequency inputsignal inputted into the reception block, so as to form a close circuitwith the low-noise amplifier or a variable attenuator selectively, thelevel of the high frequency input signal depending on a distance from ahost machine (an apparatus such an access point, a router or the like;or a transmitting box or the like).

Taking the embodiment 1 as an example, the following describes settingof a threshold of the communication distance, which corresponds with theRSSI value: to which level the threshold value is set. The followingrefers to FIG. 8 in which simulation data are shown.

Conditions for a simulation regarding a communication distance(reachable distance) between the host machine and the client are asfollows.

Supposing that a signal route has no obstacles; an ideal isotropictransmitting antenna and an ideal isotropic receiving antenna arerespectively set within a range of sight (sight distance); and only anelectric wave directly transmitting between these antennas (direct wave)is used. A value of received voltage (Pr) captured from a transmittedvoltage (Pt) is dependent only on a distance between the antennas (d),and on a wavelength (λ) of a frequency in use; thus, Pr is calculated informulas below:Pr=Pt×(λ/4πd)=Pt/(4πd/λ)²  (1),Pr=Pt×(λ/4πd)^(2.5) =Pt/(4πd/λ)^(2.5)  (2),Pr=Pt×(λ/4πd)³ =Pt/(4πd/λ) ³  (3).

Thus, (4πd/λ)² or ^(2.5) or ³=Pt/Pr=Lp.

Note that Lp is so-called free space transmission loss.

A power law 2 of a formula (1) indicates an ideal free space. A 2.5thpower law of a formula (2), indicating conditions of a space(environment) in general use, is a generally used exponent deriving fromempirical rules. A power 3 of a formula (3) is a power based on asupposition of an office space (environment) in which desks, lockers,and people are frequently moving.

Note that, in actually designing the communication apparatus, one of theformulas 1 to 3 is selected according to which one of the power laws(2nd, 2.5th, 3rd power laws) the communication environment isapproximate to.

Where directive gain (absolute gain (dBi)) of the transmitting antennaand the receiving antenna are respectively Gt and Gr, the free spacetransmission loss is calculated as follows:Pr=Pt*Gt*(1/Lp)*Gr,and the free space transmission loss is expressed in decibel as follows:Pr(dBm)=Pt(dBm)+Gt(dB)−10 log Lp+Gr(dB).

The tables in FIG. 8 are programmed to perform spreadsheet-usingcalculation of the distance (d) by using the converted formula.

According to FIG. 8(e) showing a result of the simulation with the 2.5thpower law, representing a use in the general space, it is expected thatthere will be no problems for a communication taking place within arange of 26 meters (at-home communication). Therefore, in case ofdesigning the communication apparatus for the communication environmentthat follows the 2.5th power law, the threshold value of the RSSI valueis set to a value corresponding to the communication distance of 26meters. With this arrangement, the power amplifier for transmission isautomatically turned OFF accordingly when the RSSI value is equal to orhigher than the threshold value, according to the present invention.

Further, when recognizing that the distance has become farther than 26meters by the RSSI (that is, when the RSSI value is lower than thethreshold value), the power amplifier 9 is automatically turned on. Withsuch setting that signal passing through the power amplifier 9, thecommunication range is expanded up to 107 meters as shown in FIG. 8(b).

Moreover, even for office environments in which many obstacle structuresare packed jumblingly in space, it is expected, from a result ofsimulation with the third power law shown in FIG. 8(f), that there willbe no problems for a communication that is taken place within a-range of7 meters despite such harsh conditions. Therefore, for designing thecommunication apparatus for the communication environment following thethird power law, the threshold value of the RSSI value is set to be avalue suitable for the communication distance of 7 meters. With thisarrangement, the power amplifier for transmission in the presentinvention is automatically turned off accordingly when the RSSI value isequal to or higher than the RSSI value, according to the presentinvention.

Further, when recognizing that the distance has become farther than 7meters by the RSSI, the power amplifier 9 is automatically turned on.With such setting that signal passing through the power amplifier 9, thecommunication range is expanded up to 22 meters as shown in FIG. 8(c).

A simulation data in FIG. 9 shows the threshold setting of the foregoingembodiment 4 (turning ON and OFF of the low-noise amplifier 4 forreception). Conditions and calculations for the simulation are the sameas that of the FIG. 8. Thus, description is omitted.

Embodiment 7

The following describes an example in which (a) a communication state isevaluated by using various signals generated by a communication protocolthat sets a control method for transmission and reception of acommunication apparatus, and a power amplifier 9 or a low-noiseamplifier 4 is turned ON and OFF by using a result of the evaluation ofthe communication state.

FIG. 16 shows an arrangement of a server, a client, and a terminal (EP;End Point) regarding the protocol for executing an application forcommunication between the server and client via a wireless LAN (LocalArea Network), such as voice communication, video delivery, and the likecommunication, which are performed between the server and client (forexample in case of streaming later described), between terminals (EP)(for example, in case of VoIP later described).

Some of specific examples for such applications are streaming and VoiP(Voice over Internet Protocol).

The streaming and VoIP are applications for performing reproduction ofmultimedia data as receiving the multimedia data. Here, streaming refersto an application for one-way transmission of multimedia data from theserver to the client, thereby distinguishing the streaming from theVoIP, which performs two-way communication. VoIP is an application fortwo-way communication on an IP network. VoIP is used for, for example,telephone (that is, two-way voice communication), and two-waycommunication of an image or voice, and the like two-way communication.

In the communication using the wireless LAN, the terminal (EP), theserver, and the client have hierarchical structures in which they have 7layers, as shown in FIG. 16.

A first layer (RF; Radio Frequency) is a physical layer and set acommunication standard (for example, IEEE 802.11b) for actual wirelesscommunication via an access point (AP).

A second layer (MAC/BB; Media Access Control/Back Baseband) is a datalink layer and sets a protocol for transmitting and receiving data in aform of a packet.

A third layer (IP; Internet Protocol) is a network layer and sets aprotocol for delivery of data from a computer to a computer.

A fourth layer (UDP/TCP; User Datagaram

Protocol/Transmission Control Protocol) is a transport layer, and sets aprotocol regarding control procedure for keeping high quality ofcommunication so that all packets can be delivered to a communicationcounterpart without errors.

A fifth layer (RTP; Real Time Protocol) is a presentation layer, andsets a protocol regarding packet format for use in continuous datacommunication for video data or audio data.

A sixth layer (receive buffer) (reception buffer)) is a lower layer ofan application layer. The sixth layer sets a protocol for temporalholding of the packets. After reception, the packets, which areformatted in accordance with RTP before their transmission, aretemporally held for a certain number of packets, depending on which kindof application is used.

A seventh layer (video, audio, RTVP; Real Time Control Protocol) is anupper layer of the application layer, and sets a protocol regarding (a)interface process for decoding of the video data, audio data, the likedata encoded in accordance with RTP, and (b) control process fordefining relationship between terminals (communication apparatuses).

FIG. 17 shows various information to be inputted into the controller 18for stopping and allowing the power supply for the low-noise amplifier 4and the power amplifier 9. The various information is obtained via dataprocessing based on various protocol explained in FIG. 16. As laterdescried, the various information regards condition of the communication(communication state) between the server and the client. By referring tothe various information, the controller 18 causes the generating section18 a to generate the first control signal that is suitable for thecommunication state, and causes the control section 18 b to generate thesecond control signal. The controller 18 sends the first and secondcontrol signals to an RF circuit section 43, which serves as a receptorcircuit section and a transmitter circuit section, which include thelow-noise amplifier 4 and the power amplifier 9.

With this arrangement, the controller 18 evaluates the evaluation of thecommunication state. According to a result of the evaluation performedby the controller 18, controlled is (i) the switching-over between theamplification route (in which the signal passes through the low-noiseamplifier 4 or the power amplifier 9) and the bypass route 22 (32), and(ii) the turning-ON/OFF of the low-noise amplifier 4 or the poweramplifier 9 when the bypass route 22 (32) is selected.

The various information may be TCP information, UDP information, RTPinformation, RTCP information, A/V (audio/video) media information,and/or receive buffer information.

TCP information is generated by the data processing in accordance withTCP of the fourth layer. TCP is a protocol with which it is possible toconfirm whether the data transmitted is correctly received by acounterpart communication apparatus. If the data is received correctly,the counterpart communication apparatus transmits ack (acknowledgement)information to a communication apparatus (transmission-performingcommunication apparatus) that transmitted the data. Thus, by receivingthe ack information from the counterpart communication apparatus, thetransmission-performing communication apparatus can confirm that thecounterpart communication apparatus received the data correctly (withouterrors).

TCP is a protocol for repeating the transmission of the data until thereception of the ack information or until repeating the transmitting apredetermined time, if the ack information is not received by TCP withina predetermined timeout period. Therefore, a threshold value may be setin terms of how many times the transmission is repeated, and thethreshold value may be used to indicate how the communication state is.Moreover, the threshold value may be in multi levels.

UDP information is generated by the data processing in accordance withUDP of the fourth layer. UDP information is information showing a degreeof errors in the data thus received. That is, the UDP information isgenerated by a process (checksum) for judging the degree of errors, theprocess executed by USP. Note that UDP is a protocol for a simplecommunication procedure with which only the information necessary forcommunicating the data with the application layer is generated. In thepresent embodiment, the video data and the audio data are transmitted toa reception-performing communication apparatus in accordance with RTPand UDP described below,) the reception-performing communicationapparatus being a communication apparatus receiving the data from itscounterpart communication apparatus.

The UDP information may also be information indicative of two conditionsregarding errors, that is, whether the data thus received has an erroror not, or may also be information indicating how the condition is, byusing a threshold, which may be multileveled.

The RTP information, which is generated by a data processing inaccordance with RTP of the fifth layer, is information regarding (i) anumber of packets to be transmitted by the transmission-performingcommunication apparatus (the number of packets following the packetcontaining that RTP information), and (ii) time (time stamp) at whichthe reception-performing communication apparatus is expected to receivethe data (the packets). Because the RTP information is sent from thetransmission-performing communication apparatus to thereception-performing communication apparatus, the reception-performingcommunication apparatus, the reception-performing communicationapparatus can know which kind of data the reception-performing willreceived.

However, the reception-performing communication apparatus may ignorepackets that are lost during the communication, and that are deliveredbehind time, and sequentially reproduce only packets that thereception-performing communication apparatus received within the timeduring witch the reception-performing communication apparatus isexpected to receive the packets. The reception-performing communicationapparatus may reproduce the packets that are delivered behind time,without processing the packets. In this regards, any arrangement may beadapted depending on the design of the application.

The RTCP information is information (SR; sender report) regardingcommunication state such as a degree of congestion in the network, areception speed (rate) of the reception-performing communicationcounterpart, the number of packets of data to be transmitted from themoment by the transmission-performing communication apparatus, and thetime during which the reception-performing communication apparatus isexpected to receive the packets. The use of RTCP allows to vary thetransmission speed (rate) and transmission amount of the multimedia dataaccording to situation, whereas RTP dose not have such function.

The A/V media information is information or the like, which is generatedby application of the seventh layer, and which is (i) the informationsuch as the video data, audio data and/or the like, (ii) informationregarding time in which the audio and/or video data is to be reproduced,(iii) information indicative of whether error-resilience tool (errorcorrector) operates or not, the error-resilience tool provided in avideo CODEC (Compression and DECompressin) or an audio CODEC, and/or(iv) the like information. When an error (for example, part of the datais missing), is found, the error-resilience tool interpolates orcorrects data having the error.

The receive buffer information is generated by the sixth layer and isinformation regarding time necessary for storing the data in a receivebuffer, the data received by the reception-performing communicationapparatus. Note that the receive buffer information will be descriedlater.

Next, explained is the case where the controller 18 judges that thecommunication state is good, and the controller 18 thus causes thegenerating section 18 a to generate the first control signal that is forcausing the signal to bypass the low-noise amplifier 4 or the poweramplifier 9, and causes the control section 18 b to generate the secondcontrol signal that is for stopping the supply of the power to thelow-noise amplifier 4 and the power amplifier 9.

(1) Judgment Based on TCP Information

For the reception-performing communication apparatus, in case thereception-performing communication apparatus sends, to thetransmission-performing communication apparatus, ack by TCP, but doesnot send nack (retransmission request) to the transmission-performingcommunication apparatus, the controller 18 of the reception-performingcommunication apparatus judges, based on such TCP information, that thecommunication state is good. Consequently, the controller 18 stops thesupply of the power to the low-noise amplifier 4 by using the controlsection 18 b.

On the other hand, for the transmission-performing communicationapparatus, in case the transmission-performing communication apparatusdoes receives ack but not nack by TCP, the controller 18 of thetransmission-performing communication apparatus judges, based on suchTCP information, that the communication state is good. Consequently, thecontroller 18 stops the supply of the power to the power amplifier 9 byusing the control section 18 b.

(2) Judgment Based on UDP Information

In case where the checksum of UDP finds no error in thereception-performing communication apparatus, or finds that, in thereception-performing communication apparatus, the degree of the error isequal to or less than the threshold value, the controller 18 of thereception-performing communication apparatus judges, based on such UDPinformation, that the communication state is good. Consequently, thecontroller 18 of the reception-performing communication apparatus stopsthe supply of the power to the low-noise amplifier 4 by using thelow-noise amplifier 4.

(3) Judgment Based on RTP Information and RTCP Information

In case where, in the reception-performing communication apparatus,comparison between the RTP information and SR of RTCP is performed andan actual reception state of the received data accords with forecastedreception state of data, the controller 18 of the reception-performingcommunication apparatus judges, based on such RTP information and RTCPinformation, that the communication is good. Consequently, thecontroller 18 of the reception-performing communication apparatus stopsthe supply of the power to the low-noise amplifier 4 by using thecontroller 18 b.

Note that the RTP information is information obtained by finding out howmany packets the reception-performing communication apparatus hasreceived, how much byte the received packets are, how many packets thereception-performing communication apparatus received per second, and/orthe like.

(4) Judgment Based on RTP Information and A/V Media Information

In case as a result of comparison between packet arrival time indicated(examined) by RTP and the A/V media information (the informationregarding the time to reproduce (or decode) the data) received by thereception-performing communication end, the comparison found that thepacket arrival time is earlier than the time to reproduce the data, thecontroller 18 of the reception-performing communication apparatusjudges, based on such RTP information and A/V media information, thatthe communication state is good. Consequently, the controller 18 of thereception-performing communication apparatus stops the supply of thepower to the low-noise amplifier 4 by using the control section 18 b. Ifthe packet arrival time (time at which the packet is received) isearlier than the time to reproduce the data, this indicates that thereception-performing communication apparatus receives the data withsufficient time before the time to reproduce the data.

This point is explained more specifically below. For example, in case ofthe video signal, the video signal is sampled per 33 msec as unit oftime unit, thereby forming coded data whose one frame has a period of 33msec, as shown in FIG. 18(a), that is, the video signal is convertedinto the coded data v1, v2, v3, and v4, for example. Each frame has aheader into which a time since the start time of the sampling iswritten.

In FIG. 18(a), the coded data v1 and the like are shown to have variousdata length. This is because, in case of the video data, a data amountvaries time to time depending on type and nature of images: a stillpicture or a dynamic picture; a dynamic picture showing a very activelymoving object or showing a rather motionless object.

Times (t, t+a, t+b, t+c) at which the coded data v1 and the like aretransmitted from the server to the client are continuous. However, timesat which the coded data v1 and the like are received by the client isnot continuous. That is, the communication state between the server andclient affects and changes the times at which the coded data v1 and thelike are received by the client.

Because of this, as shown in FIG. 18(a), such a phenomenon possiblyoccurs that, for example, the data v1 is received by the client in timebefore time T at which the data v1 is to be reproduced, but the data v3fails to be received in time before time T+2 at which the data v3supposed to be reproduced.

Note that the client reads time information from the header of eachframe, by using RTP, thereby grasping the times at which the frames areto be reproduced respectively.

FIG. 18(b) shows a case where the same treatment is done for the audiosignal. In case of the audio signal, for example in AMR (adaptivemultirate coder), coded data is prepared by sampling the audio signalper 20sec as unit of time, thereby preparing coded data divided intoframes of 20 sec. As in the video signal, each frame has a header inwhich a time passed from the starting time of the sampling is written.

In case of the audio signal, the data amount to be coded with respect tothe constant sampling time is basically constant. Thus, as shown in FIG.18(b), coded data v′1, v′2, v′3, v′4 of the audio signal have the samedata length. As to the transmission time and the time to reproduce thedata, the same is true as in the case of the video signal.

(5) Judgment Based on A/V Media Information

In case where in the reception-performing communication apparatus theerror-resilience tool provided in the video CODEC or the audio CODEC isnot operated, the controller 18 of the reception-performingcommunication apparatus judges, based on such A/V media information,that the communication state is good. Consequently, the controller 18 ofthe reception-performing communication apparatus stops the supply of thepower to the low-noise amplifier 4 by using the control section 18 b.

The following discuses the opposite case, that is, in case where thecontroller 18 judges that the communication state is bad, andconsequently allows the supply of the power to the low-amplifier 4 orthe power-amplifier 9 by using the control section 18 b.

(1) Judgment Based on TCP Information

For reception-performing communication apparatus, in case thereception-performing communication apparatus sends nack to thetransmission-performing communication apparatus by TCP consequently an nnumber of times, the controller 18 of the communication apparatusjudges, based on such TCP information, that the communication state isbad. Consequently, the controller 18 of the reception-performingcommunication apparatus allows the supply of the power to the low-noiseamplifier 4 by using the control section 18 b.

On the other hand, for the transmission-performing communicationapparatus, if the transmission-performing communication apparatusreceives nack from the reception-performing communication apparatus byTCP consequently the n number of times, the controller 18 of thetransmission-performing communication apparatus may be so arranged tojudge, based on such TCP information, that the communication state isbad, and consequently to allow the supply of the power to the poweramplifier 9 by using the control section 18 b.

Note that the example discussed above is merely an example. The judgmentmay be made referring to thresholds as to how many times nack occurs perunit of time, instead of how many times nack occurs sequentially.Alternatively, the threshold values as to (a) how many times nack occursper unit of time, and (b) how many times nack occurs sequentially, maybe set considering a relationship of the data length of the packet with(a) how many times nack occurs per unit of time, and (b) how many timesnack occurs sequentially. (For example, the threshold is set larger,when the data length is long.)

(2) Judgment Based on UDP Information

In case where in the reception-performing communication apparatus thechecksum of UDP found an error or found that the degree of errorsexceeds the threshold value, the controller 18 of thereception-performing communication apparatus judges, based on such UDPinformation, that the communication state is bad. Consequently, thecontroller 18 allows the supply of the power to the low-amplifier 4 byusing the control section 18 b. Note that the threshold value may be settaking into consideration a relationship between the degree of errorsand the data length of the packets.

(3) Judgment Based on RTP Information and RTCP Information

In case where, in the reception-performing communication apparatus,comparison between the RTP information and SR of RTCP is performed andfound that an actual state of the received data does not accord with aforecasted state of the data (the forecasted state is notified beforethe signal is received), the controller 18 of the reception-performingcommunication apparatus judges, based on such RTP information and RTCPinformation, that the communication is bad. Consequently, the controller18 of the reception-performing communication apparatus allows the supplyof the power to the low-noise amplifier 4 by using the controller 18 b.

(4) Judgment Based on RTP Information and A/V Media Information

In case as a result of comparison between packet arrival time indicated(examined) by RTP and the A/V media information (the informationregarding the time to reproduce (or decode) the data) received by thereception-performing communication end, the comparison found that thepacket arrival time arrived on or after the time to reproduce the data,the controller 18 of the reception-performing communication apparatusjudges, based on such RTP information and A/V media information, thatthe communication state is bad. Consequently, the controller 18 of thereception-performing communication apparatus allows the supply of thepower to the low-noise amplifier 4 by using the control section 18 b.

(5) Judgment Based on A/V Media Information

In case where in the reception-performing communication apparatus theerror-resilience tool provided in the video CODEC or the audio CODECdoes operate, the controller 18 of the reception-performingcommunication apparatus judges, based on such A/V media information,that the communication state is bad. Consequently, the controller 18 ofthe reception-performing communication apparatus allows the supply ofthe power to the low-noise amplifier 4 by using the control section 18b.

For example, in the compressing coding method (which follows MREG-4) forthe video signal, the coded data is generated from the video signal inaccordance with a certain protocol. It may be arranged that judgment asto whether or not the coded data has an error, is conducted by whetheror not the error-resilience tool correctly detects error detection-usedata when decoding the coded data, the error detection-use datafollowing the certain protocol. If the error-resilience tool detects anerror in the coded data as a result of the judgment, theerror-resilience tool performs the error correction.

It may be arranged that the result of the judgment performed in thereception-performing communication apparatus as to whether thecommunication is good or bad, is reported to the transmission-performingcommunication apparatus, and the power amplifier 9 of thetransmission-performing communication apparatus is turned ON and OFF inaccordance with the result of the judgment performed in thereception-performing communication apparatus.

If, in the transmission-performing communication apparatus, it isimpossible to detect that the communication is bad (so that thetransmission-performing communication apparatus will turn OFF the poweramplifier 9 voluntarily) but, the reception-performing communicationapparatus detects that the communication state is bad, then, forexample, the communication apparatuses performing the communicationbetween each other carry out such control that the power is supplied tothe low-noise amplifier 4 in the reception-performing communicationapparatus, meanwhile the power-amplifier 9 of thetransmission-performing communication apparatus is supplied with thepower. As a result, in some cases, the communication becomes goodsynergistically.

On the contrary, in such a situation that the power amplifier 9 of thetransmission-performing communication apparatus is turned ON because theRSSI is small, the communication apparatuses performing thecommunication between each other can carry out such control that thereception-performing communication apparatus, which detects that thecommunication state is good, reports to the transmission-performingcommunication apparatus that the communication state is good, and thesupply of the power is stopped not only to the low-noise amplifier 4 ofthe reception-performing communication apparatus, but also to thepower-amplifier 9 of the transmission-performing communicationapparatus. This results in synergistic effect to save communicationconsumption of both the communication apparatus.

(6) Judgment Unique in Streaming and VoIP

Next, the control for turning ON and OFF is described below, which isunique in the applications of the streaming and VoIP. The turning ON andOFF of the power supply (whether the supply of the power is stopped orallowed) is controlled differently in the applications because thereceive buffer is used in different ways in the applications.

To begin with, in the streaming, in which the data is one-waytransmitted from the server to the client, the use does not recognizesretention of the data in the receive buffer in the client, even if datais retained in the receive buffer to some extent. This is because,regardless of whether or not the data is retained in the receive buffer,the user merely senses (sees and/or hears) the data that is sent out ofthe receive buffer and reproduced. Actually, a reproduction that is morenatural can be attained by reproducing the data that is transmitted tothe application after being retained in the receive buffer to someextent, because the communication speed (rate) varies time to timedepending on the condition of the network.

The client receives, from the server, information regarding bit rate (T)and necessary buffer size (b) of the data that is to be transmitted fromthe server. By doing this, the time (buffer-full time t) necessary tostore the data in the receive buffer can be found by the client by usinga formula of t=B/T (sec). The judgment whether the communication stateis good or bad is carried out by the comparison performed by thecontroller 18 to compare between (a) the buffer-full time obtained fromthe calculation and (b) time t′, which is an actual time taken to storethe data in the receive buffer, the data received (t and t′ correspondto the receive buffer information). Specifically, in the bufferingprocess carried out by the client, when t′≦t, the controller 18 judgesthat the communication is good. Consequently, the controller 18 stopsthe supply of the power to the low-noise amplifier 4 by using thecontrol section 18 b.

On the other hand, in the buffering process of the client, when t′≧t,the controller 18 judges that the communication state becomes bad.Consequently, the controller 18 allows the supply of the power to thelow-noise amplifier 4 by using the controller 18. Moreover, in thestreaming, if the receive buffer becomes empty during the reception ofdata, this indicates that the reception of data is behind time. Thus,the controller 18 judges that the communication becomes bad.Consequently, the controller 18 allows the supply of the power to thelow-noise amplifier 4 by using the control section 18 b.

Note that the buffer size (B) that the server requests the client variesdepending on how much the contents is. Therefore, the buffer size (B) isinconstant. Moreover, the bit rate (T) also varies depending on how mucha communication line is crowded. In the client, when a scheduled dataamount is retained the receive buffer, the data is sent from the receivebuffer to the application, so that the reproduction of the data isstarted.

The receive buffer has a memory capacity larger than the buffer size(B). Thus, it is possible to retain the received data in the receivebuffer even if a data amount inputted into the receive buffer exceeds adata amount outputted from the receive buffer. Moreover, it is possiblefor the server to grasp the size of the receive buffer of the client,and a data amount that can be transmitted to the client.

Next, in VoIP, conversation is established by the two-way audiocommunication between the server and the client or between thecommunications apparatuses. Thus, VoIP is so arranged that VoIP does notallow delay in the reception of the audio data basically. Therefore, nobuffering process is carried out in VoIP, unlike the streaming.

In VoIP, if the reception-performing communication apparatus can decodethe audio data continuously during the conversation, the controller 18receives the A/V media information notifying this state. Hereby, thecontroller 18 judges that the communication state is good. Consequently,the controller 18 stops the supply of the power to the low-noiseamplifier 4 by using the control section 18 b.

On the other hand, if the decoding of the audio data is stopped duringthe conversation, the controller 18 receives the A/V media informationnotifying this state. Hereby, the controller 18 judges that thecommunication state becomes bad. Consequently, the controller 18 allowsthe supply of the power to the low-noise amplifier 4 by using thecontrol section 18 b.

Note that, if the conversation is paused, the audio CODEC detects thatno audio input is inputted. Consequently, the audio CODEC generatesno-voice information and sends it to the counterpart communicationapparatus. Thus, the decoding of the audio data is kept to becontinuous.

So far, described is how to carry out by the controller 18 the judgmentas to whether the communication state is good or bad, by using thevarious signals generated by the communication protocol. In the above,the process of the judgment is divided into the judgments (1) to (6).The following explains an order of carrying out the judgments (1) to(6), and collateral condition to the judgments (1) to (6) in order tostop or allow the supply of the power to the low-noise amplifier 4.

The judgment (1) to (6) are carried out in this order (their numbering).This order is the same as an order in which the judgments are carriedout in accordance with the communication protocol. Therefore, in theorder of from (1) to (6), the controller 18 carries the judgment as towhether the communication state is good or bad.

For the first method in which the supply of the power to the low-noiseamplifier 4 is allowed if the collateral condition is satisfied, thecollateral condition is that if any one of the judgments (1) to (6)showed at least one phenomenon indicating that the communication stateis bad, the controller 18 would judge that the communication state isbad, and allow the supply of the power to the low-noise amplifier 4 byusing the control section 18 b.

Moreover, for the second method in which the supply of the power of thelow-noise amplifier 4 is allowed if the collateral condition issatisfied, its collateral conditions are (a) that if any one of thejudgments (1) to (4) showed at least one phenomenon indicating that thecommunication state is bad, the controller 18 would judge that thecommunication state is bad, and allow the supply of the power to thelow-noise amplifier 4 by using the control section 18 b, and (b) thatfor the judgments (5) and (6), the phenomenon indicating that thecommunication state is bad is tolerated until it occurs n times, whichis a threshold for the allowance of the phenomenon, and if thephenomenon occurs n times, the controller 18 would judge thatcommunication state is bad, and would allow the supply of the power tothe low-noise amplifier 4 by using the control section 18 b.

Note that in the second method, the judgments (1) to (4) are not limitedto such arrangement that the controller 18 judges that the communicationstate is bad if the phenomenon occurs at least one time. That is, it maybe so arranged as to set threshold values to the judgments (1) to (6)respectively as to the tolerance as to how many number of times thephenomenon is tolerated to occur, as long as the threshold values do notadversely affect the reliability of the communication.

Moreover, as to the threshold of n times, such collateral condition maybe set that if the phenomenon occurred continuously, or if thephenomenon occurred within a predetermined time interval, the controller18 would judge that the communication state is bad.

Further, for the first method in which the supply of the power to thelow-noise amplifier 4 is stopped if the collateral condition issatisfied, the controller 18 would judge that the communication state isgood, if in all of the judgments (1) to (6) the phenomenon indicatingthe communication state is bad did not occur. Consequently, thecontroller 18 would stop the supply of the power to the low-noiseamplifier 4 by using the control section 18 b.

Further, for the second method in which the supply of the power of thelow-noise amplifier 4 is stopped if the collateral condition issatisfied, the controller 18 would judge that the communication state isgood, if in the judgments (1) to (4) the phenomenon did not occur. Then,for time being, the controller 18 would stop the supply of the power tothe low-noise amplifier 4. The controller 18 counts the number of thetimes the phenomenon occurs as to the judgments (5) and (6). If theoccurrence of the phenomenon is counted up to the threshold value forany one of the judgments (5) and (6), the controller 18 judge that thecommunication state becomes bad. Consequently, the controller 18 allowsthe supply of the power to the low-noise amplifier 4 by using thecontrol section 18 b.

Further, for the third method in which the supply of the power to thelow-noise amplifier 4 is stopped if the collateral condition issatisfied, the threshold values for the judgments (1) to (6) arerespectively set as to the tolerance as to how many number of times thephenomenon is tolerated to occur, as long as the threshold values do notadversely affect the reliability of the communication. Until at leastone of the thresholds is exceeded by the number of times the phenomenonoccurs, the controller 18 judges that the communication is good. So, thecontroller 18 stops the supply of the power to the low-noise amplifier 4by using the control section 18 b.

Hereinafter, other characteristics of the present invention are listedbelow.

(1) It is preferable that, in the wireless communication circuit, acontrol means (controller) controls switching-over of the first switchin accordance with a strength of a reception signal.

Therefore, it is possible to appropriately judge the distance betweenthe apparatuses performing the wireless communication, and to switchover to the bypass route timely when the distance is short. Thereby, itis possible to attain that the communication can be continued longertime without recharging the battery. Furthermore, the wirelesscommunication can be surely performed with lower power consumption.

(2) It is preferable that, in the wireless communication circuit, thecontrol means (controller) includes a generating section for generatinga first control signal that is for controlling the switching-over of thefirst switch, in accordance with a received signal strength indicator,which is the strength of the reception signal.

With this arrangement, it is possible to attain a simpler circuitconfiguration by using the RSSI, which is normally provided in a digitalsignal processing circuit, such as a baseband signal processing circuitsection.

(3) It is preferable that the wireless communication circuit furthercomprises a second switch for allowing and stopping supply of power tothe amplifier, the control means (controller) having a control sectionfor generating a second control signal that is for controlling thesecond switch in concert with the switching-over of the first switch.

With this arrangement, it is possible to stop the supply of the power tothe amplifier by using the second switch, when the bypass route isselected. Thus, it is possible to reduce the power consumption, therebyprolonging the duration of the battery.

(4) The wireless communication circuit may comprise a fixed attenuatoron the bypass route. The wireless communication circuit may comprise avariable attenuator on the bypass route.

When the distance from the host machine is so short, the distortion isdeteriorated and the sensitivity is reduced. This arrangement not onlyattains the “improvement of a battery duration” and “energy-savingdesign”, but also allows the communication apparatus to becommunicatable in a more vicinity of the host machine by improving thedistortion by the attenuation amount of the (fixed or variable)attenuator when the route in which the signal passes the attenuator isselected. Further, the arrangement in which the variable attenuator isprovided is more advantageous for communication that is carried outwhile location is changing (eg. by a user who is walking) time to time,such as communications carried out with PDA, portable phone or the like.

Furthermore, for the case where a large number of communicationapparatuses perform communication at once within a certain area (such aswireless LAN), the arrangement in which the bypass route includes thefixed attenuator or the variable attenuator is more advantageous becauseit is possible to reduce the output of the transmission signals fromeach of the communication counterparts when they are in a closedistance. Further, it is possible to suppress occupying communicationband used by other wireless communication apparatus, or interferingcommunication by other wireless communication apparatus.

(5) The wireless communication circuit may be so arranged that theamplifier is a power amplifier for amplifying a transmission signal thatis to be sent to the antenna. The wireless communication circuit may beso arranged that the amplifier is a low-noise amplifier for amplifying areception signal received via the antenna. With this arrangement, “animprovement of a battery durability” and “an energy-saving design” canbe achieved. Especially, in case of the power amplifier, those can beattained to a large extent with certainty.

(6) A wireless communication circuit of the present invention, includingan amplifier for amplifying a signal, the wireless communication circuitcomprising: an amplification route in which the signal passes throughthe amplifier; a bypass route for bypassing the amplifier; and aroute-selector for selecting one of the amplification route and thebypass route.

One of the objects of the present invention is to provide a wirelesscommunication circuit that allows both (a) an apparatus in which thecircuit is provide, and (b) a counter apparatus performing communicationwith the apparatus, to perform high-quality communication with low powerconsumption.

Moreover, an unamplified signal can be transmitted with less distortionand without disturbing other communication apparatuses. For bettertransmission and reception, it is possible to select by the bypass routeby using the route-selector, in order that the communication may becarried out with the unamplified signal. In this case, because theamplifier is not used, the power consumption of the wirelesscommunication circuit can be saved.

(7) It is preferable to arrange such that the route-selector selects oneof the amplification route and the bypass route in accordance with astrength of the signal (signal strength) that the wireless communicationcircuit receives.

With this arrangement, it is possible to switch over between theamplification route and the bypass route, in accordance with the signalstrength, which changes time to time depending on the communicationdistance and the communication environment (surrounding)

(8) It is preferable to arrange such that the route-selector selects thebypass route when the strength of the signal received is equal to orhigher than a predetermined threshold value.

With this arrangement, when the strength of the signal received is equalto or higher than the predetermined threshold value, and thus there isno need of amplifying the strength of the reception signal, the bypassroute is selected. Hence, it is possible to attain high-qualitycommunication with low power consumption.

(9) It is preferable to arrange such that the route-selector has acontrol means (controller) for judging whether communication of thewireless communication circuit is good or bad, and for generating afirst control signal that is for selecting one of the amplificationroute and the bypass route in accordance with a result of the judging.

With this arrangement, it is possible to switch over between theamplification route and the bypass route, taking into considerationvarious factors, which relate to the judgment of the communicationstate. That is, it is possible to attain delicate control of the powerconsumption by controlling the power consumption in accordance morevarious factors.

(10) It is arranged that the route-selector has a control means(controller) for judging whether communication state of the wirelesscommunication circuit is good or bad, and for generating a first controlsignal that is for selecting one of the amplification route and thebypass route in accordance with a result of the judging; and when thecontrol means judges that the communication state is good even if astrength of the signal received is equal to or lower than apredetermined threshold value, the control means generates a firstcontrol signal that is for selecting the bypass route.

In the previous arrangements, when the strength of the signal is equalto or less than the threshold, the reception signal should be amplifiedin some cases because the reception signal received by the wirelesscommunication circuit is weak. However, there is no problem with suchweak reception signal, provided that the communication state is good.According to this arrangement, in which not only the strength of thereception signal is judged, but also the communication state isevaluated, it is possible to attain more effective control for realizinglow power consumption.

(11) It is arranged that the route-selector has a control means(controller) for judging whether communication state of the wirelesscommunication circuit is good or bad, and for generating a first controlsignal that is for selecting one of the amplification route and thebypass route in accordance with a result of the judging; and when thecontrol means judges that the communication state is bad even if astrength of the signal received is equal to or higher than apredetermined threshold value, the control means generates a firstcontrol signal that is for selecting the amplification route.

In the previous arrangements, when the strength of the signal is equalto or higher than the threshold, application of the reception signal isunnecessary in some case because the reception signal received by thewireless communication circuit is strong. However, no high-qualitycommunication can be attained if the communication state is bad.According to this arrangement, in which not only the strength of thereception signal is judged, but also the communication state isevaluated, it is possible to improve reliability of communication whiletaking the low power consumption into consideration.

(12) Note that the control means (controller) judges that thecommunication state is good, when:

-   -   (a) the control means (controller) analyzes contents of an        information signal received from the counterpart communication        apparatus, and judges an information signal as “ack”        (appropriate reception acknowledgement);    -   (b) the control means (controller) detects the degree of errors        in the reception data generated from the signal received by the        wireless communication circuit, and the degree of error does not        exceeds the threshold value;    -   (c) an actual reception state of reception data generated from a        signal received by the wireless communication circuit, accords        with a forecasted reception state of the reception data, the        forecasted reception state being notified from a counterpart        communication apparatus before the signal is received.

(d) (i) the control means (controller) obtains a time information fromreception data, which is generated from a signal received by thewireless communication circuit, the time information regarding a time atwhich application for the reception data is to be executed, (ii) thecontrol means compares, with the time information, a time at which thereception data is received, and (iii) the control means judges that thereception data of the signal arrived before the time at which theapplication is to be executed;

-   -   (e) an error-resilience tool is not operated, the        error-resilience tool provided in an application using reception        data, which is generated from a signal received by the wireless        communication circuit;    -   (f) t′≦t, where the wireless communication circuit is provided        with a receive buffer for temporally retaining reception data,        and reception data generated from a signal received by the        wireless communication circuit is streaming data, the control        means (controller) receives information from a communication        apparatus that is to transmit the reception data, the        information regarding a bit rate of the reception data and a        buffer size that is necessary for temporally retaining the        reception data, the control means obtaining a buffer-full time t        from the bit rate and the buffer size, the buffer-full time t        being a time necessary for storing the reception data in the        receive buffer, the control means comparing the buffer-full time        t with a buffering time t′, which is an actual time taken to        store the reception data in the receive buffer;    -   (g) reception data generated from a signal received by a        wireless communication circuit, in which the wireless        communication circuit is provided, is continuously decoded,        where the communication apparatus including the wireless        communication circuit performs two-way communication with a        counterpart communication apparatus; and the like conditions.

Therefore, while being executed, the application, which uses thereception data generated from the signal received by the wirelesscommunication circuit, is monitored in terms of the various factors, asto whether the application is appropriately executed. When theapplication is appropriately executed, it is possible to select thelow-power-consumption mode in which the bypass route is use. Further, byfurther taking into consideration the judgment as to the strength of thereception signal used for the judgment as to the communication state, itis possible to attain more effective control for realizing low powerconsumption.

Note that it may be arranged such that (h) the receive buffer becomesempty during reception of the reception data, the control means judgesthat the communication state is bad.

In this case, the emptiness of the receive buffer during the receptionof the reception data indicates that the reception of the reception datais hindered. One of possible counter-measurements for thereception-performing communication apparatus is to amplify the strengthof the reception signal by selecting the amplification route.

(13) Further, it may be arranged such that, regarding the conditions (a)to (i), a threshold value is set as to a number of times the controlmeans judges that the communication state is bad, and while the numberof times is less than or equal to the threshold value, the control meansjudges that the communication state is good.

With this arrangement, in which the threshold value can be set dependingon how much reliability of communication is needed, it is possible toattain flexible control for realizing the low power consumption, whileensuring reliability of communication to some extent.

(14) Further, the wireless communication circuit of the presentinvention is so arranged as to include a power-supply stopper forstopping supply of power to the amplifier in concert with selecting ofthe bypass route by the route-selector.

With this arrangement, it is possible to further reduces the powerconsumption, and for example, to prolong the duration of the built-inbattery, because the power-supply stopper for stopping supply of powerto the amplifier in concert with selecting of the bypass route by theroute-selector. Moreover, this arrangement prevents noise from mixinginto the bypass route form the amplification route.

(15) A wireless communication circuit of the present invention having anamplifier for amplifying a signal, is so arranged as to comprise acommunication-distance-detector for detecting a distance from acommunication counterpart; and a route-selector for selecting, inaccordance with the distance detected (found out) by thecommunication-distance-detector, one of (a) an amplification route inwhich the signal passes through the amplifier, and (b) a bypass route inwhich the signal bypasses the amplifier.

When the distance from the communication counterpart is short, thesignal transmitted from the communication counterpart tends to bestrong, whereas the signal transmitted from the communicationcounterpart tends to be weak. With this arrangement, it is possible tocontrol the power consumption in accordance with the receptioncondition, by switching over between the amplification route and thebypass route in accordance with the thus detected distance.

Note that the communication-distance-detector may be provided with (a) adetector for detecting the strength of the reception signal, (b) astorage for storing data that associates the strength of the receptionsignal with the communication distance, and (c) a judgment section forjudging, based on (by using) the data, a communication distanceassociated with the strength thus detected.

(16) It may be so arranged that the route-selector selects the bypassroute, when the distance from the communication counterpart exceeds apredetermined value, the distance detected (found out) by thecommunication-distance-detector.

With this arrangement, it is possible to attain a similar effect as inthe arrangement where the bypass route is selected when the strength ofthe signal is equal to or higher than a predetermined threshold value.

The embodiments and concrete examples of implementation discussed in theforegoing detailed explanation serve solely to illustrate the technicaldetails of the present invention, which should not be narrowlyinterpreted within the limits of such embodiments and concrete examples,but rather may be applied in many variations within the spirit of thepresent invention, provided such variations do not exceed the scope ofthe patent claims set forth below.

1. A wireless communication circuit for a terminal for transmitting andreceiving information, the wireless communication circuit comprising: anantenna; an amplifier to be connected to the antenna; a bypass route forbypassing a signal route passing the amplifier; and a first switch forswitching over to select one of (a) the signal route passing theamplifier and (b) the bypass route.
 2. The wireless communicationcircuit as set forth in claim 1 further comprising: a controller forcontrolling switching-over of the first switch in accordance with astrength of a reception signal.
 3. The wireless communication circuit asset forth in claim 2 wherein: the controller includes a generatingsection for generating a first control signal that is for controllingthe switching-over of the first switch, in accordance with a receivedsignal strength indicator, which is the strength of the receptionsignal.
 4. The wireless communication circuit as set forth in claim 2,further comprising: a second switch for allowing and stopping supply ofpower to the amplifier, the controller having a control section forgenerating a second control signal that is for controlling the secondswitch in concert with the switching-over of the first switch.
 5. Thewireless communication circuit as set forth in claim 1 furthercomprising: a fixed attenuator on the bypass route.
 6. The wirelesscommunication circuit as set forth in claim 1 further comprising: avariable attenuator on the bypass route.
 7. The wireless communicationcircuit as set forth in claim 1 wherein: the amplifier is a poweramplifier for amplifying a transmission signal that is to be sent to theantenna.
 8. The wireless communication circuit as set forth in claim 1wherein: the amplifier is a low-noise amplifier for amplifying areception signal received via the antenna.
 9. A wireless communicationapparatus, comprising: a wireless communication circuit for a terminalfor transmitting and receiving information, the wireless communicationcircuit including: an antenna; an amplifier to be connected to theantenna; a bypass route for bypassing a signal route passing theamplifier; and a first switch for switching over to select one of (a)the signal route passing the amplifier and (b) the bypass route.
 10. Awireless communication system comprising: a wireless communicationapparatus having a wireless communication circuit for a terminal fortransmitting and receiving information, the wireless communicationapparatus including: a wireless communication apparatus having: anantenna; an amplifier to be connected to the antenna; a bypass route forbypassing a signal route passing the amplifier; and a first switch forswitching over to select one of (a) the signal route passing theamplifier and (b) the bypass route.
 11. A wireless communication circuitincluding an amplifier for amplifying a signal, the wirelesscommunication circuit comprising: an amplification route in which thesignal passes through the amplifier; a bypass route for bypassing theamplifier; and a route-selector for selecting one of the amplificationroute and the bypass route.
 12. The wireless communication circuit asset forth in claim 11 wherein: the route-selector selects one of theamplification route and the bypass route in accordance with a strengthof the signal that the wireless communication circuit receives.
 13. Thewireless communication circuit as set forth in claim 12 wherein: theroute-selector selects the bypass route when the strength of the signalreceived is equal to or higher than a predetermined threshold value. 14.The wireless communication circuit as set forth in claim 11 wherein: theroute-selector has a controller for judging whether communication stateof the wireless communication circuit is good or bad, and for generatinga first control signal that is for selecting one of the amplificationroute and the bypass route in accordance with a result of the judging.15. The wireless communication circuit as set forth in claim 11 wherein:the route-selector has a controller for judging whether communicationstate of the wireless communication circuit is good or bad, and forgenerating a first control signal that is for selecting one of theamplification route and the bypass route in accordance with a result ofthe judging; and when the controller judges that the communication stateis good even if a strength of the signal received is equal to or lowerthan a predetermined threshold value, the controller generates a firstcontrol signal that is for selecting the bypass route.
 16. The wirelesscommunication circuit as set forth in claim 11 wherein: theroute-selector has a controller for judging whether communication stateof the wireless communication circuit is good or bad, and for generatinga first control signal that is for selecting one of the amplificationroute and the bypass route in accordance with a result of the judging;and when the controller judges that the communication state is bad evenif a strength of the signal received is equal to or higher than apredetermined threshold value, the controller generates a first controlsignal that is for selecting the amplification route.
 17. The wirelesscommunication circuit as set forth in claim 14 wherein: when thewireless communication circuit receives no retransmission request from acounterpart communication apparatus to which the wireless communicationcircuit sent an information signal, the controller judges that thecommunication state is good.
 18. The wireless communication circuit asset forth in claim 14 wherein: (a) the controller detects a degree oferrors in reception data, which is generated from a signal received bythe wireless communication circuit, and (b) when the degree of errorsdoes not exceed a threshold value, the controller judges that thecommunication state is good.
 19. The wireless communication circuit asset forth in claim 14 wherein: when an actual reception state ofreception data generated from a signal received by the wirelesscommunication circuit, accords with a forecasted reception state of thereception data, the controller judges that the communication is good,the forecasted reception state being notified from a counterpartcommunication apparatus before the signal is received.
 20. The wirelesscommunication circuit as set forth in claim 14 wherein: (a) thecontroller obtains a time information from reception data, which isgenerated from a signal received by the wireless communication circuit,the time information regarding a time at which application for thereception data is to be executed, (b) the controller compares, with thetime information, a time at which the signal is received, and (c) whenthe controller judges that the reception data of the signal arrivedbefore the time at which the application is to be executed, thecontroller judges that the communication state is good.
 21. The wirelesscommunication circuit as set forth in claim 14 wherein: when anerror-resilience tool is not operated, the controller judges that thecommunication state is good, the error-resilience tool provided in anapplication using reception data, which is generated from a signalreceived by the wireless communication circuit.
 22. The wirelesscommunication circuit as set forth in claim 14, comprising: a receivebuffer for temporally retaining reception data when reception datagenerated from a signal received by the wireless communication circuitis streaming data, the controller receiving information from acommunication apparatus that is to transmit the reception data, theinformation regarding a bit rate of the reception data and a buffer sizethat is necessary for temporally retaining the reception data, thecontroller obtaining a buffer-full time t from the bit rate and thebuffer size, the buffer-full time t being a time necessary for storingthe reception data in the receive buffer, the controller comparing thebuffer-full time t with a buffering time t′, which is an actual timetaken to store the reception data in the receive buffer, and when t′≦t,the controller judging that the communication state is good.
 23. Thewireless communication circuit as set forth in claim 22, wherein: whenthe receive buffer becomes empty during reception of the reception data,the controller judges that the communication state is bad.
 24. Thewireless communication circuit as set forth in claim 14, wherein: whenreception data generated from a signal received by a wirelesscommunication circuit, in which the wireless communication circuit isprovided, is continuously decoded, the controller judges that thecommunication state is good, where a communication apparatus includingthe wireless communication circuit performs two-way communication with acounterpart communication apparatus.
 25. The wireless communicationcircuit as set forth in claim 14, wherein: a threshold value is set asto a number of times the controller judges that the communication stateis bad, and while the number of times is less than or equal to thethreshold value, the controller judges that the communication state isgood.
 26. The wireless communication circuit as set forth in claim 11,comprising: a power-supply stopper for stopping supply of power to theamplifier in concert with selecting of the bypass route by theroute-selector.
 27. The wireless communication circuit as set forth inclaim 12, comprising: a power-supply stopper for stopping supply ofpower to the amplifier in concert with selecting of the bypass route bythe route-selector.
 28. The wireless communication circuit as set forthin claim 13, comprising: a power-supply stopper for stopping supply ofpower to the amplifier in concert with selecting of the bypass route bythe route-selector.
 29. The wireless communication circuit as set forthin claim 14, comprising: a power-supply stopper for stopping supply ofpower to the amplifier in concert with selecting of the bypass route bythe route-selector.
 30. The wireless communication circuit as set forthin claim 15, comprising: a power-supply stopper for stopping supply ofpower to the amplifier in concert with selecting of the bypass route bythe route-selector.
 31. The wireless communication circuit as set forthin claim 16, comprising: a power-supply stopper for stopping supply ofpower to the amplifier in concert with selecting of the bypass route bythe route-selector.
 32. The wireless communication circuit as set forthin claim 11, wherein: the amplifier is a power amplifier for amplifyinga signal to be transmitted.
 33. The wireless communication circuit asset forth in claim 11 wherein: the amplifier is a low-noise amplifierfor amplifying a signal received.
 34. The wireless communication circuitas set forth in claim 11 wherein: the bypass route has an attenuator forattenuating the signal.
 35. The wireless communication circuit as setforth in claim 11 wherein: the bypass route has a variable attenuatorfor attenuating the signal with a variable attenuation amount.
 36. Awireless communication apparatus, comprising: a wireless communicationcircuit having an amplifier for amplifying a signal, the wirelesscommunication circuit including: an amplification route in which thesignal passes through the amplifier; a bypass route for bypassing theamplifier; and a route-selector for selecting one of the amplificationroute and the bypass route.
 37. A wireless communication systemincluding a wireless communication apparatus, wherein: the wirelesscommunication apparatus comprising: a wireless communication circuithaving an amplifier for amplifying a signal, the wireless communicationcircuit including: an amplification route in which the signal passesthrough the amplifier; a bypass route for bypassing the amplifier; and aroute-selector for selecting one of the amplification route and thebypass route.
 38. A wireless communication circuit having an amplifierfor amplifying a signal, comprising: a communication-distance-detectorfor detecting a distance from a communication counterpart; and aroute-selector for selecting, in accordance with the distance found outby the communication-distance-detector, one of (a) an amplificationroute in which the signal passes through the amplifier, and (b) a bypassroute in which the signal bypasses the amplifier.
 39. The wirelesscommunication circuit as set forth in claim 38 wherein: thecommunication-distance-detector detects the distance, by using astrength of the signal received from the communication counterpart. 40.The wireless communication circuit as set forth in claim 38 wherein: theroute-selector selects the bypass route, when the distance from thecommunication counterpart exceeds a predetermined value, the distancefound out by the communication-distance-detector.
 41. A wirelesscommunication apparatus comprising: a wireless communication circuithaving an amplifier for amplifying a signal, the wireless communicationcircuit including: a communication-distance-detector for detecting adistance from a communication counterpart; and a route-selector forselecting, in accordance with the distance found out by thecommunication-distance-detector, one of (a) an amplification route inwhich the signal passes through the amplifier, and (b) a bypass route inwhich the signal bypasses the amplifier.
 42. A wireless communicationsystem comprising: a wireless communication apparatus including: awireless communication circuit having an amplifier for amplifying asignal, the wireless communication circuit including: acommunication-distance-detector for detecting a distance from acommunication counterpart; and a route-selector for selecting, inaccordance with the distance found out by thecommunication-distance-detector, one of (a) an amplification route inwhich the signal passes through the amplifier, and (b) a bypass route inwhich the signal bypasses the amplifier.